bootstrap.bundle.js

   * is right.<br />
   * Vertically (`left` and `right`), `start` is top and `end` is bottom.
   *
   * Some valid examples are:
   * - `top-end` (on top of reference, right aligned)
   * - `right-start` (on right of reference, top aligned)
   * - `bottom` (on bottom, centered)
   * - `auto-end` (on the side with more space available, alignment depends by placement)
   *
   * @static
   * @type {Array}
   * @enum {String}
   * @readonly
   * @method placements
   * @memberof Popper
   */
  var placements = ['auto-start', 'auto', 'auto-end', 'top-start', 'top', 'top-end', 'right-start', 'right', 'right-end', 'bottom-end', 'bottom', 'bottom-start', 'left-end', 'left', 'left-start'];

  // Get rid of `auto` `auto-start` and `auto-end`
  var validPlacements = placements.slice(3);

  /**
   * Given an initial placement, returns all the subsequent placements
   * clockwise (or counter-clockwise).
   *
   * @method
   * @memberof Popper.Utils
   * @argument {String} placement - A valid placement (it accepts variations)
   * @argument {Boolean} counter - Set to true to walk the placements counterclockwise
   * @returns {Array} placements including their variations
   */
  function clockwise(placement) {
    var counter = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : false;

    var index = validPlacements.indexOf(placement);
    var arr = validPlacements.slice(index + 1).concat(validPlacements.slice(0, index));
    return counter ? arr.reverse() : arr;
  }

  var BEHAVIORS = {
    FLIP: 'flip',
    CLOCKWISE: 'clockwise',
    COUNTERCLOCKWISE: 'counterclockwise'
  };

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function flip(data, options) {
    // if `inner` modifier is enabled, we can't use the `flip` modifier
    if (isModifierEnabled(data.instance.modifiers, 'inner')) {
      return data;
    }

    if (data.flipped && data.placement === data.originalPlacement) {
      // seems like flip is trying to loop, probably there's not enough space on any of the flippable sides
      return data;
    }

    var boundaries = getBoundaries(data.instance.popper, data.instance.reference, options.padding, options.boundariesElement, data.positionFixed);

    var placement = data.placement.split('-')[0];
    var placementOpposite = getOppositePlacement(placement);
    var variation = data.placement.split('-')[1] || '';

    var flipOrder = [];

    switch (options.behavior) {
      case BEHAVIORS.FLIP:
        flipOrder = [placement, placementOpposite];
        break;
      case BEHAVIORS.CLOCKWISE:
        flipOrder = clockwise(placement);
        break;
      case BEHAVIORS.COUNTERCLOCKWISE:
        flipOrder = clockwise(placement, true);
        break;
      default:
        flipOrder = options.behavior;
    }

    flipOrder.forEach(function (step, index) {
      if (placement !== step || flipOrder.length === index + 1) {
        return data;
      }

      placement = data.placement.split('-')[0];
      placementOpposite = getOppositePlacement(placement);

      var popperOffsets = data.offsets.popper;
      var refOffsets = data.offsets.reference;

      // using floor because the reference offsets may contain decimals we are not going to consider here
      var floor = Math.floor;
      var overlapsRef = placement === 'left' && floor(popperOffsets.right) > floor(refOffsets.left) || placement === 'right' && floor(popperOffsets.left) < floor(refOffsets.right) || placement === 'top' && floor(popperOffsets.bottom) > floor(refOffsets.top) || placement === 'bottom' && floor(popperOffsets.top) < floor(refOffsets.bottom);

      var overflowsLeft = floor(popperOffsets.left) < floor(boundaries.left);
      var overflowsRight = floor(popperOffsets.right) > floor(boundaries.right);
      var overflowsTop = floor(popperOffsets.top) < floor(boundaries.top);
      var overflowsBottom = floor(popperOffsets.bottom) > floor(boundaries.bottom);

      var overflowsBoundaries = placement === 'left' && overflowsLeft || placement === 'right' && overflowsRight || placement === 'top' && overflowsTop || placement === 'bottom' && overflowsBottom;

      // flip the variation if required
      var isVertical = ['top', 'bottom'].indexOf(placement) !== -1;
      var flippedVariation = !!options.flipVariations && (isVertical && variation === 'start' && overflowsLeft || isVertical && variation === 'end' && overflowsRight || !isVertical && variation === 'start' && overflowsTop || !isVertical && variation === 'end' && overflowsBottom);

      if (overlapsRef || overflowsBoundaries || flippedVariation) {
        // this boolean to detect any flip loop
        data.flipped = true;

        if (overlapsRef || overflowsBoundaries) {
          placement = flipOrder[index + 1];
        }

        if (flippedVariation) {
          variation = getOppositeVariation(variation);
        }

        data.placement = placement + (variation ? '-' + variation : '');

        // this object contains `position`, we want to preserve it along with
        // any additional property we may add in the future
        data.offsets.popper = _extends({}, data.offsets.popper, getPopperOffsets(data.instance.popper, data.offsets.reference, data.placement));

        data = runModifiers(data.instance.modifiers, data, 'flip');
      }
    });
    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function keepTogether(data) {
    var _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var placement = data.placement.split('-')[0];
    var floor = Math.floor;
    var isVertical = ['top', 'bottom'].indexOf(placement) !== -1;
    var side = isVertical ? 'right' : 'bottom';
    var opSide = isVertical ? 'left' : 'top';
    var measurement = isVertical ? 'width' : 'height';

    if (popper[side] < floor(reference[opSide])) {
      data.offsets.popper[opSide] = floor(reference[opSide]) - popper[measurement];
    }
    if (popper[opSide] > floor(reference[side])) {
      data.offsets.popper[opSide] = floor(reference[side]);
    }

    return data;
  }

  /**
   * Converts a string containing value + unit into a px value number
   * @function
   * @memberof {modifiers~offset}
   * @private
   * @argument {String} str - Value + unit string
   * @argument {String} measurement - `height` or `width`
   * @argument {Object} popperOffsets
   * @argument {Object} referenceOffsets
   * @returns {Number|String}
   * Value in pixels, or original string if no values were extracted
   */
  function toValue(str, measurement, popperOffsets, referenceOffsets) {
    // separate value from unit
    var split = str.match(/((?:\-|\+)?\d*\.?\d*)(.*)/);
    var value = +split[1];
    var unit = split[2];

    // If it's not a number it's an operator, I guess
    if (!value) {
      return str;
    }

    if (unit.indexOf('%') === 0) {
      var element = void 0;
      switch (unit) {
        case '%p':
          element = popperOffsets;
          break;
        case '%':
        case '%r':
        default:
          element = referenceOffsets;
      }

      var rect = getClientRect(element);
      return rect[measurement] / 100 * value;
    } else if (unit === 'vh' || unit === 'vw') {
      // if is a vh or vw, we calculate the size based on the viewport
      var size = void 0;
      if (unit === 'vh') {
        size = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
      } else {
        size = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);
      }
      return size / 100 * value;
    } else {
      // if is an explicit pixel unit, we get rid of the unit and keep the value
      // if is an implicit unit, it's px, and we return just the value
      return value;
    }
  }

  /**
   * Parse an `offset` string to extrapolate `x` and `y` numeric offsets.
   * @function
   * @memberof {modifiers~offset}
   * @private
   * @argument {String} offset
   * @argument {Object} popperOffsets
   * @argument {Object} referenceOffsets
   * @argument {String} basePlacement
   * @returns {Array} a two cells array with x and y offsets in numbers
   */
  function parseOffset(offset, popperOffsets, referenceOffsets, basePlacement) {
    var offsets = [0, 0];

    // Use height if placement is left or right and index is 0 otherwise use width
    // in this way the first offset will use an axis and the second one
    // will use the other one
    var useHeight = ['right', 'left'].indexOf(basePlacement) !== -1;

    // Split the offset string to obtain a list of values and operands
    // The regex addresses values with the plus or minus sign in front (+10, -20, etc)
    var fragments = offset.split(/(\+|\-)/).map(function (frag) {
      return frag.trim();
    });

    // Detect if the offset string contains a pair of values or a single one
    // they could be separated by comma or space
    var divider = fragments.indexOf(find(fragments, function (frag) {
      return frag.search(/,|\s/) !== -1;
    }));

    if (fragments[divider] && fragments[divider].indexOf(',') === -1) {
      console.warn('Offsets separated by white space(s) are deprecated, use a comma (,) instead.');
    }

    // If divider is found, we divide the list of values and operands to divide
    // them by ofset X and Y.
    var splitRegex = /\s*,\s*|\s+/;
    var ops = divider !== -1 ? [fragments.slice(0, divider).concat([fragments[divider].split(splitRegex)[0]]), [fragments[divider].split(splitRegex)[1]].concat(fragments.slice(divider + 1))] : [fragments];

    // Convert the values with units to absolute pixels to allow our computations
    ops = ops.map(function (op, index) {
      // Most of the units rely on the orientation of the popper
      var measurement = (index === 1 ? !useHeight : useHeight) ? 'height' : 'width';
      var mergeWithPrevious = false;
      return op
      // This aggregates any `+` or `-` sign that aren't considered operators
      // e.g.: 10 + +5 => [10, +, +5]
      .reduce(function (a, b) {
        if (a[a.length - 1] === '' && ['+', '-'].indexOf(b) !== -1) {
          a[a.length - 1] = b;
          mergeWithPrevious = true;
          return a;
        } else if (mergeWithPrevious) {
          a[a.length - 1] += b;
          mergeWithPrevious = false;
          return a;
        } else {
          return a.concat(b);
        }
      }, [])
      // Here we convert the string values into number values (in px)
      .map(function (str) {
        return toValue(str, measurement, popperOffsets, referenceOffsets);
      });
    });

    // Loop trough the offsets arrays and execute the operations
    ops.forEach(function (op, index) {
      op.forEach(function (frag, index2) {
        if (isNumeric(frag)) {
          offsets[index] += frag * (op[index2 - 1] === '-' ? -1 : 1);
        }
      });
    });
    return offsets;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @argument {Number|String} options.offset=0
   * The offset value as described in the modifier description
   * @returns {Object} The data object, properly modified
   */
  function offset(data, _ref) {
    var offset = _ref.offset;
    var placement = data.placement,
        _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var basePlacement = placement.split('-')[0];

    var offsets = void 0;
    if (isNumeric(+offset)) {
      offsets = [+offset, 0];
    } else {
      offsets = parseOffset(offset, popper, reference, basePlacement);
    }

    if (basePlacement === 'left') {
      popper.top += offsets[0];
      popper.left -= offsets[1];
    } else if (basePlacement === 'right') {
      popper.top += offsets[0];
      popper.left += offsets[1];
    } else if (basePlacement === 'top') {
      popper.left += offsets[0];
      popper.top -= offsets[1];
    } else if (basePlacement === 'bottom') {
      popper.left += offsets[0];
      popper.top += offsets[1];
    }

    data.popper = popper;
    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function preventOverflow(data, options) {
    var boundariesElement = options.boundariesElement || getOffsetParent(data.instance.popper);

    // If offsetParent is the reference element, we really want to
    // go one step up and use the next offsetParent as reference to
    // avoid to make this modifier completely useless and look like broken
    if (data.instance.reference === boundariesElement) {
      boundariesElement = getOffsetParent(boundariesElement);
    }

    // NOTE: DOM access here
    // resets the popper's position so that the document size can be calculated excluding
    // the size of the popper element itself
    var transformProp = getSupportedPropertyName('transform');
    var popperStyles = data.instance.popper.style; // assignment to help minification
    var top = popperStyles.top,
        left = popperStyles.left,
        transform = popperStyles[transformProp];

    popperStyles.top = '';
    popperStyles.left = '';
    popperStyles[transformProp] = '';

    var boundaries = getBoundaries(data.instance.popper, data.instance.reference, options.padding, boundariesElement, data.positionFixed);

    // NOTE: DOM access here
    // restores the original style properties after the offsets have been computed
    popperStyles.top = top;
    popperStyles.left = left;
    popperStyles[transformProp] = transform;

    options.boundaries = boundaries;

    var order = options.priority;
    var popper = data.offsets.popper;

    var check = {
      primary: function primary(placement) {
        var value = popper[placement];
        if (popper[placement] < boundaries[placement] && !options.escapeWithReference) {
          value = Math.max(popper[placement], boundaries[placement]);
        }
        return defineProperty({}, placement, value);
      },
      secondary: function secondary(placement) {
        var mainSide = placement === 'right' ? 'left' : 'top';
        var value = popper[mainSide];
        if (popper[placement] > boundaries[placement] && !options.escapeWithReference) {
          value = Math.min(popper[mainSide], boundaries[placement] - (placement === 'right' ? popper.width : popper.height));
        }
        return defineProperty({}, mainSide, value);
      }
    };

    order.forEach(function (placement) {
      var side = ['left', 'top'].indexOf(placement) !== -1 ? 'primary' : 'secondary';
      popper = _extends({}, popper, check[side](placement));
    });

    data.offsets.popper = popper;

    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function shift(data) {
    var placement = data.placement;
    var basePlacement = placement.split('-')[0];
    var shiftvariation = placement.split('-')[1];

    // if shift shiftvariation is specified, run the modifier
    if (shiftvariation) {
      var _data$offsets = data.offsets,
          reference = _data$offsets.reference,
          popper = _data$offsets.popper;

      var isVertical = ['bottom', 'top'].indexOf(basePlacement) !== -1;
      var side = isVertical ? 'left' : 'top';
      var measurement = isVertical ? 'width' : 'height';

      var shiftOffsets = {
        start: defineProperty({}, side, reference[side]),
        end: defineProperty({}, side, reference[side] + reference[measurement] - popper[measurement])
      };

      data.offsets.popper = _extends({}, popper, shiftOffsets[shiftvariation]);
    }

    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function hide(data) {
    if (!isModifierRequired(data.instance.modifiers, 'hide', 'preventOverflow')) {
      return data;
    }

    var refRect = data.offsets.reference;
    var bound = find(data.instance.modifiers, function (modifier) {
      return modifier.name === 'preventOverflow';
    }).boundaries;

    if (refRect.bottom < bound.top || refRect.left > bound.right || refRect.top > bound.bottom || refRect.right < bound.left) {
      // Avoid unnecessary DOM access if visibility hasn't changed
      if (data.hide === true) {
        return data;
      }

      data.hide = true;
      data.attributes['x-out-of-boundaries'] = '';
    } else {
      // Avoid unnecessary DOM access if visibility hasn't changed
      if (data.hide === false) {
        return data;
      }

      data.hide = false;
      data.attributes['x-out-of-boundaries'] = false;
    }

    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function inner(data) {
    var placement = data.placement;
    var basePlacement = placement.split('-')[0];
    var _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var isHoriz = ['left', 'right'].indexOf(basePlacement) !== -1;

    var subtractLength = ['top', 'left'].indexOf(basePlacement) === -1;

    popper[isHoriz ? 'left' : 'top'] = reference[basePlacement] - (subtractLength ? popper[isHoriz ? 'width' : 'height'] : 0);

    data.placement = getOppositePlacement(placement);
    data.offsets.popper = getClientRect(popper);

    return data;
  }

  /**
   * Modifier function, each modifier can have a function of this type assigned
   * to its `fn` property.<br />
   * These functions will be called on each update, this means that you must
   * make sure they are performant enough to avoid performance bottlenecks.
   *
   * @function ModifierFn
   * @argument {dataObject} data - The data object generated by `update` method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {dataObject} The data object, properly modified
   */

  /**
   * Modifiers are plugins used to alter the behavior of your poppers.<br />
   * Popper.js uses a set of 9 modifiers to provide all the basic functionalities
   * needed by the library.
   *
   * Usually you don't want to override the `order`, `fn` and `onLoad` props.
   * All the other properties are configurations that could be tweaked.
   * @namespace modifiers
   */
  var modifiers = {
    /**
     * Modifier used to shift the popper on the start or end of its reference
     * element.<br />
     * It will read the variation of the `placement` property.<br />
     * It can be one either `-end` or `-start`.
     * @memberof modifiers
     * @inner
     */
    shift: {
      /** @prop {number} order=100 - Index used to define the order of execution */
      order: 100,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: shift
    },

    /**
     * The `offset` modifier can shift your popper on both its axis.
     *
     * It accepts the following units:
     * - `px` or unit-less, interpreted as pixels
     * - `%` or `%r`, percentage relative to the length of the reference element
     * - `%p`, percentage relative to the length of the popper element
     * - `vw`, CSS viewport width unit
     * - `vh`, CSS viewport height unit
     *
     * For length is intended the main axis relative to the placement of the popper.<br />
     * This means that if the placement is `top` or `bottom`, the length will be the
     * `width`. In case of `left` or `right`, it will be the `height`.
     *
     * You can provide a single value (as `Number` or `String`), or a pair of values
     * as `String` divided by a comma or one (or more) white spaces.<br />
     * The latter is a deprecated method because it leads to confusion and will be
     * removed in v2.<br />
     * Additionally, it accepts additions and subtractions between different units.
     * Note that multiplications and divisions aren't supported.
     *
     * Valid examples are:
     * ```
     * 10
     * '10%'
     * '10, 10'
     * '10%, 10'
     * '10 + 10%'
     * '10 - 5vh + 3%'
     * '-10px + 5vh, 5px - 6%'
     * ```
     * > **NB**: If you desire to apply offsets to your poppers in a way that may make them overlap
     * > with their reference element, unfortunately, you will have to disable the `flip` modifier.
     * > You can read more on this at this [issue](https://github.com/FezVrasta/popper.js/issues/373).
     *
     * @memberof modifiers
     * @inner
     */
    offset: {
      /** @prop {number} order=200 - Index used to define the order of execution */
      order: 200,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: offset,
      /** @prop {Number|String} offset=0
       * The offset value as described in the modifier description
       */
      offset: 0
    },

    /**
     * Modifier used to prevent the popper from being positioned outside the boundary.
     *
     * A scenario exists where the reference itself is not within the boundaries.<br />
     * We can say it has "escaped the boundaries" — or just "escaped".<br />
     * In this case we need to decide whether the popper should either:
     *
     * - detach from the reference and remain "trapped" in the boundaries, or
     * - if it should ignore the boundary and "escape with its reference"
     *
     * When `escapeWithReference` is set to`true` and reference is completely
     * outside its boundaries, the popper will overflow (or completely leave)
     * the boundaries in order to remain attached to the edge of the reference.
     *
     * @memberof modifiers
     * @inner
     */
    preventOverflow: {
      /** @prop {number} order=300 - Index used to define the order of execution */
      order: 300,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: preventOverflow,
      /**
       * @prop {Array} [priority=['left','right','top','bottom']]
       * Popper will try to prevent overflow following these priorities by default,
       * then, it could overflow on the left and on top of the `boundariesElement`
       */
      priority: ['left', 'right', 'top', 'bottom'],
      /**
       * @prop {number} padding=5
       * Amount of pixel used to define a minimum distance between the boundaries
       * and the popper. This makes sure the popper always has a little padding
       * between the edges of its container
       */
      padding: 5,
      /**
       * @prop {String|HTMLElement} boundariesElement='scrollParent'
       * Boundaries used by the modifier. Can be `scrollParent`, `window`,
       * `viewport` or any DOM element.
       */
      boundariesElement: 'scrollParent'
    },

    /**
     * Modifier used to make sure the reference and its popper stay near each other
     * without leaving any gap between the two. Especially useful when the arrow is
     * enabled and you want to ensure that it points to its reference element.
     * It cares only about the first axis. You can still have poppers with margin
     * between the popper and its reference element.
     * @memberof modifiers
     * @inner
     */
    keepTogether: {
      /** @prop {number} order=400 - Index used to define the order of execution */
      order: 400,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: keepTogether
    },

    /**
     * This modifier is used to move the `arrowElement` of the popper to make
     * sure it is positioned between the reference element and its popper element.
     * It will read the outer size of the `arrowElement` node to detect how many
     * pixels of conjunction are needed.
     *
     * It has no effect if no `arrowElement` is provided.
     * @memberof modifiers
     * @inner
     */
    arrow: {
      /** @prop {number} order=500 - Index used to define the order of execution */
      order: 500,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: arrow,
      /** @prop {String|HTMLElement} element='[x-arrow]' - Selector or node used as arrow */
      element: '[x-arrow]'
    },

    /**
     * Modifier used to flip the popper's placement when it starts to overlap its
     * reference element.
     *
     * Requires the `preventOverflow` modifier before it in order to work.
     *
     * **NOTE:** this modifier will interrupt the current update cycle and will
     * restart it if it detects the need to flip the placement.
     * @memberof modifiers
     * @inner
     */
    flip: {
      /** @prop {number} order=600 - Index used to define the order of execution */
      order: 600,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: flip,
      /**
       * @prop {String|Array} behavior='flip'
       * The behavior used to change the popper's placement. It can be one of
       * `flip`, `clockwise`, `counterclockwise` or an array with a list of valid
       * placements (with optional variations)
       */
      behavior: 'flip',
      /**
       * @prop {number} padding=5
       * The popper will flip if it hits the edges of the `boundariesElement`
       */
      padding: 5,
      /**
       * @prop {String|HTMLElement} boundariesElement='viewport'
       * The element which will define the boundaries of the popper position.
       * The popper will never be placed outside of the defined boundaries
       * (except if `keepTogether` is enabled)
       */
      boundariesElement: 'viewport'
    },

    /**
     * Modifier used to make the popper flow toward the inner of the reference element.
     * By default, when this modifier is disabled, the popper will be placed outside
     * the reference element.
     * @memberof modifiers
     * @inner
     */
    inner: {
      /** @prop {number} order=700 - Index used to define the order of execution */
      order: 700,
      /** @prop {Boolean} enabled=false - Whether the modifier is enabled or not */
      enabled: false,
      /** @prop {ModifierFn} */
      fn: inner
    },

    /**
     * Modifier used to hide the popper when its reference element is outside of the
     * popper boundaries. It will set a `x-out-of-boundaries` attribute which can
     * be used to hide with a CSS selector the popper when its reference is
     * out of boundaries.
     *
     * Requires the `preventOverflow` modifier before it in order to work.
     * @memberof modifiers
     * @inner
     */
    hide: {
      /** @prop {number} order=800 - Index used to define the order of execution */
      order: 800,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: hide
    },

    /**
     * Computes the style that will be applied to the popper element to gets
     * properly positioned.
     *
     * Note that this modifier will not touch the DOM, it just prepares the styles
     * so that `applyStyle` modifier can apply it. This separation is useful
     * in case you need to replace `applyStyle` with a custom implementation.
     *
     * This modifier has `850` as `order` value to maintain backward compatibility
     * with previous versions of Popper.js. Expect the modifiers ordering method
     * to change in future major versions of the library.
     *
     * @memberof modifiers
     * @inner
     */
    computeStyle: {
      /** @prop {number} order=850 - Index used to define the order of execution */
      order: 850,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: computeStyle,
      /**
       * @prop {Boolean} gpuAcceleration=true
       * If true, it uses the CSS 3D transformation to position the popper.
       * Otherwise, it will use the `top` and `left` properties
       */
      gpuAcceleration: true,
      /**
       * @prop {string} [x='bottom']
       * Where to anchor the X axis (`bottom` or `top`). AKA X offset origin.
       * Change this if your popper should grow in a direction different from `bottom`
       */
      x: 'bottom',
      /**
       * @prop {string} [x='left']
       * Where to anchor the Y axis (`left` or `right`). AKA Y offset origin.
       * Change this if your popper should grow in a direction different from `right`
       */
      y: 'right'
    },

    /**
     * Applies the computed styles to the popper element.
     *
     * All the DOM manipulations are limited to this modifier. This is useful in case
     * you want to integrate Popper.js inside a framework or view library and you
     * want to delegate all the DOM manipulations to it.
     *
     * Note that if you disable this modifier, you must make sure the popper element
     * has its position set to `absolute` before Popper.js can do its work!
     *
     * Just disable this modifier and define your own to achieve the desired effect.
     *
     * @memberof modifiers
     * @inner
     */
    applyStyle: {
      /** @prop {number} order=900 - Index used to define the order of execution */
      order: 900,
      /** @prop {Boolean} enabled=true - Whether the modifier is enabled or not */
      enabled: true,
      /** @prop {ModifierFn} */
      fn: applyStyle,
      /** @prop {Function} */
      onLoad: applyStyleOnLoad,
      /**
       * @deprecated since version 1.10.0, the property moved to `computeStyle` modifier
       * @prop {Boolean} gpuAcceleration=true
       * If true, it uses the CSS 3D transformation to position the popper.
       * Otherwise, it will use the `top` and `left` properties
       */
      gpuAcceleration: undefined
    }
  };

  /**
   * The `dataObject` is an object containing all the information used by Popper.js.
   * This object is passed to modifiers and to the `onCreate` and `onUpdate` callbacks.
   * @name dataObject
   * @property {Object} data.instance The Popper.js instance
   * @property {String} data.placement Placement applied to popper
   * @property {String} data.originalPlacement Placement originally defined on init
   * @property {Boolean} data.flipped True if popper has been flipped by flip modifier
   * @property {Boolean} data.hide True if the reference element is out of boundaries, useful to know when to hide the popper
   * @property {HTMLElement} data.arrowElement Node used as arrow by arrow modifier
   * @property {Object} data.styles Any CSS property defined here will be applied to the popper. It expects the JavaScript nomenclature (eg. `marginBottom`)
   * @property {Object} data.arrowStyles Any CSS property defined here will be applied to the popper arrow. It expects the JavaScript nomenclature (eg. `marginBottom`)
   * @property {Object} data.boundaries Offsets of the popper boundaries
   * @property {Object} data.offsets The measurements of popper, reference and arrow elements
   * @property {Object} data.offsets.popper `top`, `left`, `width`, `height` values
   * @property {Object} data.offsets.reference `top`, `left`, `width`, `height` values
   * @property {Object} data.offsets.arrow] `top` and `left` offsets, only one of them will be different from 0
   */

  /**
   * Default options provided to Popper.js constructor.<br />
   * These can be overridden using the `options` argument of Popper.js.<br />
   * To override an option, simply pass an object with the same
   * structure of the `options` object, as the 3rd argument. For example:
   * ```
   * new Popper(ref, pop, {
   *   modifiers: {
   *     preventOverflow: { enabled: false }
   *   }
   * })
   * ```
   * @type {Object}
   * @static
   * @memberof Popper
   */
  var Defaults = {
    /**
     * Popper's placement.
     * @prop {Popper.placements} placement='bottom'
     */
    placement: 'bottom',

    /**
     * Set this to true if you want popper to position it self in 'fixed' mode
     * @prop {Boolean} positionFixed=false
     */
    positionFixed: false,

    /**
     * Whether events (resize, scroll) are initially enabled.
     * @prop {Boolean} eventsEnabled=true
     */
    eventsEnabled: true,

    /**
     * Set to true if you want to automatically remove the popper when
     * you call the `destroy` method.
     * @prop {Boolean} removeOnDestroy=false
     */
    removeOnDestroy: false,

    /**
     * Callback called when the popper is created.<br />
     * By default, it is set to no-op.<br />
     * Access Popper.js instance with `data.instance`.
     * @prop {onCreate}
     */
    onCreate: function onCreate() {},

    /**
     * Callback called when the popper is updated. This callback is not called
     * on the initialization/creation of the popper, but only on subsequent
     * updates.<br />
     * By default, it is set to no-op.<br />
     * Access Popper.js instance with `data.instance`.
     * @prop {onUpdate}
     */
    onUpdate: function onUpdate() {},

    /**
     * List of modifiers used to modify the offsets before they are applied to the popper.
     * They provide most of the functionalities of Popper.js.
     * @prop {modifiers}
     */
    modifiers: modifiers
  };

  /**
   * @callback onCreate
   * @param {dataObject} data
   */

  /**
   * @callback onUpdate
   * @param {dataObject} data
   */

  // Utils
  // Methods
  var Popper = function () {
    /**
     * Creates a new Popper.js instance.
     * @class Popper
     * @param {HTMLElement|referenceObject} reference - The reference element used to position the popper
     * @param {HTMLElement} popper - The HTML element used as the popper
     * @param {Object} options - Your custom options to override the ones defined in [Defaults](#defaults)
     * @return {Object} instance - The generated Popper.js instance
     */
    function Popper(reference, popper) {
      var _this = this;

      var options = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {};
      classCallCheck(this, Popper);

      this.scheduleUpdate = function () {
        return requestAnimationFrame(_this.update);
      };

      // make update() debounced, so that it only runs at most once-per-tick
      this.update = debounce(this.update.bind(this));

      // with {} we create a new object with the options inside it
      this.options = _extends({}, Popper.Defaults, options);

      // init state
      this.state = {
        isDestroyed: false,
        isCreated: false,
        scrollParents: []
      };

      // get reference and popper elements (allow jQuery wrappers)
      this.reference = reference && reference.jquery ? reference[0] : reference;
      this.popper = popper && popper.jquery ? popper[0] : popper;

      // Deep merge modifiers options
      this.options.modifiers = {};
      Object.keys(_extends({}, Popper.Defaults.modifiers, options.modifiers)).forEach(function (name) {
        _this.options.modifiers[name] = _extends({}, Popper.Defaults.modifiers[name] || {}, options.modifiers ? options.modifiers[name] : {});
      });

      // Refactoring modifiers' list (Object => Array)
      this.modifiers = Object.keys(this.options.modifiers).map(function (name) {
        return _extends({
          name: name
        }, _this.options.modifiers[name]);
      })
      // sort the modifiers by order
      .sort(function (a, b) {
        return a.order - b.order;
      });

      // modifiers have the ability to execute arbitrary code when Popper.js get inited
      // such code is executed in the same order of its modifier
      // they could add new properties to their options configuration
      // BE AWARE: don't add options to `options.modifiers.name` but to `modifierOptions`!
      this.modifiers.forEach(function (modifierOptions) {
        if (modifierOptions.enabled && isFunction(modifierOptions.onLoad)) {
          modifierOptions.onLoad(_this.reference, _this.popper, _this.options, modifierOptions, _this.state);
        }
      });

      // fire the first update to position the popper in the right place
      this.update();

      var eventsEnabled = this.options.eventsEnabled;
      if (eventsEnabled) {
        // setup event listeners, they will take care of update the position in specific situations
        this.enableEventListeners();
      }