nouislider.js

/*! nouislider - 14.6.0 - 6/27/2020 */
(function(factory) {
    if (typeof define === "function" && define.amd) {
        // AMD. Register as an anonymous module.
        define([], factory);
    } else if (typeof exports === "object") {
        // Node/CommonJS
        module.exports = factory();
    } else {
        // Browser globals
        window.noUiSlider = factory();
    }
})(function() {
    "use strict";

    var VERSION = "14.6.0";

    //region Helper Methods

    function isValidFormatter(entry) {
        return typeof entry === "object" && typeof entry.to === "function" && typeof entry.from === "function";
    }

    function removeElement(el) {
        el.parentElement.removeChild(el);
    }

    function isSet(value) {
        return value !== null && value !== undefined;
    }

    // Bindable version
    function preventDefault(e) {
        e.preventDefault();
    }

    // Removes duplicates from an array.
    function unique(array) {
        return array.filter(function(a) {
            return !this[a] ? (this[a] = true) : false;
        }, {});
    }

    // Round a value to the closest 'to'.
    function closest(value, to) {
        return Math.round(value / to) * to;
    }

    // Current position of an element relative to the document.
    function offset(elem, orientation) {
        var rect = elem.getBoundingClientRect();
        var doc = elem.ownerDocument;
        var docElem = doc.documentElement;
        var pageOffset = getPageOffset(doc);

        // getBoundingClientRect contains left scroll in Chrome on Android.
        // I haven't found a feature detection that proves this. Worst case
        // scenario on mis-match: the 'tap' feature on horizontal sliders breaks.
        if (/webkit.*Chrome.*Mobile/i.test(navigator.userAgent)) {
            pageOffset.x = 0;
        }

        return orientation
            ? rect.top + pageOffset.y - docElem.clientTop
            : rect.left + pageOffset.x - docElem.clientLeft;
    }

    // Checks whether a value is numerical.
    function isNumeric(a) {
        return typeof a === "number" && !isNaN(a) && isFinite(a);
    }

    // Sets a class and removes it after [duration] ms.
    function addClassFor(element, className, duration) {
        if (duration > 0) {
            addClass(element, className);
            setTimeout(function() {
                removeClass(element, className);
            }, duration);
        }
    }

    // Limits a value to 0 - 100
    function limit(a) {
        return Math.max(Math.min(a, 100), 0);
    }

    // Wraps a variable as an array, if it isn't one yet.
    // Note that an input array is returned by reference!
    function asArray(a) {
        return Array.isArray(a) ? a : [a];
    }

    // Counts decimals
    function countDecimals(numStr) {
        numStr = String(numStr);
        var pieces = numStr.split(".");
        return pieces.length > 1 ? pieces[1].length : 0;
    }

    // http://youmightnotneedjquery.com/#add_class
    function addClass(el, className) {
        if (el.classList && !/\s/.test(className)) {
            el.classList.add(className);
        } else {
            el.className += " " + className;
        }
    }

    // http://youmightnotneedjquery.com/#remove_class
    function removeClass(el, className) {
        if (el.classList && !/\s/.test(className)) {
            el.classList.remove(className);
        } else {
            el.className = el.className.replace(
                new RegExp("(^|\\b)" + className.split(" ").join("|") + "(\\b|$)", "gi"),
                " "
            );
        }
    }

    // https://plainjs.com/javascript/attributes/adding-removing-and-testing-for-classes-9/
    function hasClass(el, className) {
        return el.classList
            ? el.classList.contains(className)
            : new RegExp("\\b" + className + "\\b").test(el.className);
    }

    // https://developer.mozilla.org/en-US/docs/Web/API/Window/scrollY#Notes
    function getPageOffset(doc) {
        var supportPageOffset = window.pageXOffset !== undefined;
        var isCSS1Compat = (doc.compatMode || "") === "CSS1Compat";
        var x = supportPageOffset
            ? window.pageXOffset
            : isCSS1Compat
                ? doc.documentElement.scrollLeft
                : doc.body.scrollLeft;
        var y = supportPageOffset
            ? window.pageYOffset
            : isCSS1Compat
                ? doc.documentElement.scrollTop
                : doc.body.scrollTop;

        return {
            x: x,
            y: y
        };
    }

    // we provide a function to compute constants instead
    // of accessing window.* as soon as the module needs it
    // so that we do not compute anything if not needed
    function getActions() {
        // Determine the events to bind. IE11 implements pointerEvents without
        // a prefix, which breaks compatibility with the IE10 implementation.
        return window.navigator.pointerEnabled
            ? {
                  start: "pointerdown",
                  move: "pointermove",
                  end: "pointerup"
              }
            : window.navigator.msPointerEnabled
                ? {
                      start: "MSPointerDown",
                      move: "MSPointerMove",
                      end: "MSPointerUp"
                  }
                : {
                      start: "mousedown touchstart",
                      move: "mousemove touchmove",
                      end: "mouseup touchend"
                  };
    }

    // https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md
    // Issue #785
    function getSupportsPassive() {
        var supportsPassive = false;

        /* eslint-disable */
        try {
            var opts = Object.defineProperty({}, "passive", {
                get: function() {
                    supportsPassive = true;
                }
            });

            window.addEventListener("test", null, opts);
        } catch (e) {}
        /* eslint-enable */

        return supportsPassive;
    }

    function getSupportsTouchActionNone() {
        return window.CSS && CSS.supports && CSS.supports("touch-action", "none");
    }

    //endregion

    //region Range Calculation

    // Determine the size of a sub-range in relation to a full range.
    function subRangeRatio(pa, pb) {
        return 100 / (pb - pa);
    }

    // (percentage) How many percent is this value of this range?
    function fromPercentage(range, value, startRange) {
        return (value * 100) / (range[startRange + 1] - range[startRange]);
    }

    // (percentage) Where is this value on this range?
    function toPercentage(range, value) {
        return fromPercentage(range, range[0] < 0 ? value + Math.abs(range[0]) : value - range[0], 0);
    }

    // (value) How much is this percentage on this range?
    function isPercentage(range, value) {
        return (value * (range[1] - range[0])) / 100 + range[0];
    }

    function getJ(value, arr) {
        var j = 1;

        while (value >= arr[j]) {
            j += 1;
        }

        return j;
    }

    // (percentage) Input a value, find where, on a scale of 0-100, it applies.
    function toStepping(xVal, xPct, value) {
        if (value >= xVal.slice(-1)[0]) {
            return 100;
        }

        var j = getJ(value, xVal);
        var va = xVal[j - 1];
        var vb = xVal[j];
        var pa = xPct[j - 1];
        var pb = xPct[j];

        return pa + toPercentage([va, vb], value) / subRangeRatio(pa, pb);
    }

    // (value) Input a percentage, find where it is on the specified range.
    function fromStepping(xVal, xPct, value) {
        // There is no range group that fits 100
        if (value >= 100) {
            return xVal.slice(-1)[0];
        }

        var j = getJ(value, xPct);
        var va = xVal[j - 1];
        var vb = xVal[j];
        var pa = xPct[j - 1];
        var pb = xPct[j];

        return isPercentage([va, vb], (value - pa) * subRangeRatio(pa, pb));
    }

    // (percentage) Get the step that applies at a certain value.
    function getStep(xPct, xSteps, snap, value) {
        if (value === 100) {
            return value;
        }

        var j = getJ(value, xPct);
        var a = xPct[j - 1];
        var b = xPct[j];

        // If 'snap' is set, steps are used as fixed points on the slider.
        if (snap) {
            // Find the closest position, a or b.
            if (value - a > (b - a) / 2) {
                return b;
            }

            return a;
        }

        if (!xSteps[j - 1]) {
            return value;
        }

        return xPct[j - 1] + closest(value - xPct[j - 1], xSteps[j - 1]);
    }

    function handleEntryPoint(index, value, that) {
        var percentage;

        // Wrap numerical input in an array.
        if (typeof value === "number") {
            value = [value];
        }

        // Reject any invalid input, by testing whether value is an array.
        if (!Array.isArray(value)) {
            throw new Error("noUiSlider (" + VERSION + "): 'range' contains invalid value.");
        }

        // Covert min/max syntax to 0 and 100.
        if (index === "min") {
            percentage = 0;
        } else if (index === "max") {
            percentage = 100;
        } else {
            percentage = parseFloat(index);
        }

        // Check for correct input.
        if (!isNumeric(percentage) || !isNumeric(value[0])) {
            throw new Error("noUiSlider (" + VERSION + "): 'range' value isn't numeric.");
        }

        // Store values.
        that.xPct.push(percentage);
        that.xVal.push(value[0]);

        // NaN will evaluate to false too, but to keep
        // logging clear, set step explicitly. Make sure
        // not to override the 'step' setting with false.
        if (!percentage) {
            if (!isNaN(value[1])) {
                that.xSteps[0] = value[1];
            }
        } else {
            that.xSteps.push(isNaN(value[1]) ? false : value[1]);
        }

        that.xHighestCompleteStep.push(0);
    }

    function handleStepPoint(i, n, that) {
        // Ignore 'false' stepping.
        if (!n) {
            return;
        }

        // Step over zero-length ranges (#948);
        if (that.xVal[i] === that.xVal[i + 1]) {
            that.xSteps[i] = that.xHighestCompleteStep[i] = that.xVal[i];

            return;
        }

        // Factor to range ratio
        that.xSteps[i] =
            fromPercentage([that.xVal[i], that.xVal[i + 1]], n, 0) / subRangeRatio(that.xPct[i], that.xPct[i + 1]);

        var totalSteps = (that.xVal[i + 1] - that.xVal[i]) / that.xNumSteps[i];
        var highestStep = Math.ceil(Number(totalSteps.toFixed(3)) - 1);
        var step = that.xVal[i] + that.xNumSteps[i] * highestStep;

        that.xHighestCompleteStep[i] = step;
    }

    //endregion

    //region Spectrum

    function Spectrum(entry, snap, singleStep) {
        this.xPct = [];
        this.xVal = [];
        this.xSteps = [singleStep || false];
        this.xNumSteps = [false];
        this.xHighestCompleteStep = [];

        this.snap = snap;

        var index;
        var ordered = []; // [0, 'min'], [1, '50%'], [2, 'max']

        // Map the object keys to an array.
        for (index in entry) {
            if (entry.hasOwnProperty(index)) {
                ordered.push([entry[index], index]);
            }
        }

        // Sort all entries by value (numeric sort).
        if (ordered.length && typeof ordered[0][0] === "object") {
            ordered.sort(function(a, b) {
                return a[0][0] - b[0][0];
            });
        } else {
            ordered.sort(function(a, b) {
                return a[0] - b[0];
            });
        }

        // Convert all entries to subranges.
        for (index = 0; index < ordered.length; index++) {
            handleEntryPoint(ordered[index][1], ordered[index][0], this);
        }

        // Store the actual step values.
        // xSteps is sorted in the same order as xPct and xVal.
        this.xNumSteps = this.xSteps.slice(0);

        // Convert all numeric steps to the percentage of the subrange they represent.
        for (index = 0; index < this.xNumSteps.length; index++) {
            handleStepPoint(index, this.xNumSteps[index], this);
        }
    }

    Spectrum.prototype.getDistance = function(value) {
        var index;
        var distances = [];

        for (index = 0; index < this.xNumSteps.length - 1; index++) {
            // last "range" can't contain step size as it is purely an endpoint.
            var step = this.xNumSteps[index];

            if (step && (value / step) % 1 !== 0) {
                throw new Error(
                    "noUiSlider (" +
                        VERSION +
                        "): 'limit', 'margin' and 'padding' of " +
                        this.xPct[index] +
                        "% range must be divisible by step."
                );
            }

            // Calculate percentual distance in current range of limit, margin or padding
            distances[index] = fromPercentage(this.xVal, value, index);
        }

        return distances;
    };

    // Calculate the percentual distance over the whole scale of ranges.
    // direction: 0 = backwards / 1 = forwards
    Spectrum.prototype.getAbsoluteDistance = function(value, distances, direction) {
        var xPct_index = 0;

        // Calculate range where to start calculation
        if (value < this.xPct[this.xPct.length - 1]) {
            while (value > this.xPct[xPct_index + 1]) {
                xPct_index++;
            }
        } else if (value === this.xPct[this.xPct.length - 1]) {
            xPct_index = this.xPct.length - 2;
        }

        // If looking backwards and the value is exactly at a range separator then look one range further
        if (!direction && value === this.xPct[xPct_index + 1]) {
            xPct_index++;
        }

        var start_factor;
        var rest_factor = 1;

        var rest_rel_distance = distances[xPct_index];

        var range_pct = 0;

        var rel_range_distance = 0;
        var abs_distance_counter = 0;
        var range_counter = 0;

        // Calculate what part of the start range the value is
        if (direction) {
            start_factor = (value - this.xPct[xPct_index]) / (this.xPct[xPct_index + 1] - this.xPct[xPct_index]);
        } else {
            start_factor = (this.xPct[xPct_index + 1] - value) / (this.xPct[xPct_index + 1] - this.xPct[xPct_index]);
        }

        // Do until the complete distance across ranges is calculated
        while (rest_rel_distance > 0) {
            // Calculate the percentage of total range
            range_pct = this.xPct[xPct_index + 1 + range_counter] - this.xPct[xPct_index + range_counter];

            // Detect if the margin, padding or limit is larger then the current range and calculate
            if (distances[xPct_index + range_counter] * rest_factor + 100 - start_factor * 100 > 100) {
                // If larger then take the percentual distance of the whole range
                rel_range_distance = range_pct * start_factor;
                // Rest factor of relative percentual distance still to be calculated
                rest_factor = (rest_rel_distance - 100 * start_factor) / distances[xPct_index + range_counter];
                // Set start factor to 1 as for next range it does not apply.
                start_factor = 1;
            } else {
                // If smaller or equal then take the percentual distance of the calculate percentual part of that range
                rel_range_distance = ((distances[xPct_index + range_counter] * range_pct) / 100) * rest_factor;
                // No rest left as the rest fits in current range
                rest_factor = 0;
            }

            if (direction) {
                abs_distance_counter = abs_distance_counter - rel_range_distance;
                // Limit range to first range when distance becomes outside of minimum range
                if (this.xPct.length + range_counter >= 1) {
                    range_counter--;
                }
            } else {
                abs_distance_counter = abs_distance_counter + rel_range_distance;
                // Limit range to last range when distance becomes outside of maximum range
                if (this.xPct.length - range_counter >= 1) {
                    range_counter++;
                }
            }

            // Rest of relative percentual distance still to be calculated
            rest_rel_distance = distances[xPct_index + range_counter] * rest_factor;
        }

        return value + abs_distance_counter;
    };

    Spectrum.prototype.toStepping = function(value) {
        value = toStepping(this.xVal, this.xPct, value);

        return value;
    };

    Spectrum.prototype.fromStepping = function(value) {
        return fromStepping(this.xVal, this.xPct, value);
    };

    Spectrum.prototype.getStep = function(value) {
        value = getStep(this.xPct, this.xSteps, this.snap, value);

        return value;
    };

    Spectrum.prototype.getDefaultStep = function(value, isDown, size) {
        var j = getJ(value, this.xPct);

        // When at the top or stepping down, look at the previous sub-range
        if (value === 100 || (isDown && value === this.xPct[j - 1])) {
            j = Math.max(j - 1, 1);
        }

        return (this.xVal[j] - this.xVal[j - 1]) / size;
    };

    Spectrum.prototype.getNearbySteps = function(value) {
        var j = getJ(value, this.xPct);

        return {
            stepBefore: {
                startValue: this.xVal[j - 2],
                step: this.xNumSteps[j - 2],
                highestStep: this.xHighestCompleteStep[j - 2]
            },
            thisStep: {
                startValue: this.xVal[j - 1],
                step: this.xNumSteps[j - 1],
                highestStep: this.xHighestCompleteStep[j - 1]
            },
            stepAfter: {
                startValue: this.xVal[j],
                step: this.xNumSteps[j],
                highestStep: this.xHighestCompleteStep[j]
            }
        };
    };

    Spectrum.prototype.countStepDecimals = function() {
        var stepDecimals = this.xNumSteps.map(countDecimals);
        return Math.max.apply(null, stepDecimals);
    };

    // Outside testing
    Spectrum.prototype.convert = function(value) {
        return this.getStep(this.toStepping(value));
    };

    //endregion

    //region Options

    /*	Every input option is tested and parsed. This'll prevent
        endless validation in internal methods. These tests are
        structured with an item for every option available. An
        option can be marked as required by setting the 'r' flag.
        The testing function is provided with three arguments:
            - The provided value for the option;
            - A reference to the options object;
            - The name for the option;

        The testing function returns false when an error is detected,
        or true when everything is OK. It can also modify the option
        object, to make sure all values can be correctly looped elsewhere. */

    //region Defaults

    var defaultFormatter = {
        to: function(value) {
            return value !== undefined && value.toFixed(2);
        },
        from: Number
    };

    var cssClasses = {
        target: "target",
        base: "base",
        origin: "origin",
        handle: "handle",
        handleLower: "handle-lower",
        handleUpper: "handle-upper",
        touchArea: "touch-area",
        horizontal: "horizontal",
        vertical: "vertical",
        background: "background",
        connect: "connect",
        connects: "connects",
        ltr: "ltr",
        rtl: "rtl",
        textDirectionLtr: "txt-dir-ltr",
        textDirectionRtl: "txt-dir-rtl",
        draggable: "draggable",
        drag: "state-drag",
        tap: "state-tap",
        active: "active",
        tooltip: "tooltip",
        pips: "pips",
        pipsHorizontal: "pips-horizontal",
        pipsVertical: "pips-vertical",
        marker: "marker",
        markerHorizontal: "marker-horizontal",
        markerVertical: "marker-vertical",
        markerNormal: "marker-normal",
        markerLarge: "marker-large",
        markerSub: "marker-sub",
        value: "value",
        valueHorizontal: "value-horizontal",
        valueVertical: "value-vertical",
        valueNormal: "value-normal",
        valueLarge: "value-large",
        valueSub: "value-sub"
    };

    //endregion

    function validateFormat(entry) {
        // Any object with a to and from method is supported.
        if (isValidFormatter(entry)) {
            return true;
        }

        throw new Error("noUiSlider (" + VERSION + "): 'format' requires 'to' and 'from' methods.");
    }

    function testStep(parsed, entry) {
        if (!isNumeric(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'step' is not numeric.");
        }

        // The step option can still be used to set stepping
        // for linear sliders. Overwritten if set in 'range'.
        parsed.singleStep = entry;
    }

    function testKeyboardPageMultiplier(parsed, entry) {
        if (!isNumeric(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'keyboardPageMultiplier' is not numeric.");
        }

        parsed.keyboardPageMultiplier = entry;
    }

    function testKeyboardDefaultStep(parsed, entry) {
        if (!isNumeric(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'keyboardDefaultStep' is not numeric.");
        }

        parsed.keyboardDefaultStep = entry;
    }

    function testRange(parsed, entry) {
        // Filter incorrect input.
        if (typeof entry !== "object" || Array.isArray(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'range' is not an object.");
        }

        // Catch missing start or end.
        if (entry.min === undefined || entry.max === undefined) {
            throw new Error("noUiSlider (" + VERSION + "): Missing 'min' or 'max' in 'range'.");
        }

        // Catch equal start or end.
        if (entry.min === entry.max) {
            throw new Error("noUiSlider (" + VERSION + "): 'range' 'min' and 'max' cannot be equal.");
        }

        parsed.spectrum = new Spectrum(entry, parsed.snap, parsed.singleStep);
    }

    function testStart(parsed, entry) {
        entry = asArray(entry);

        // Validate input. Values aren't tested, as the public .val method
        // will always provide a valid location.
        if (!Array.isArray(entry) || !entry.length) {
            throw new Error("noUiSlider (" + VERSION + "): 'start' option is incorrect.");
        }

        // Store the number of handles.
        parsed.handles = entry.length;

        // When the slider is initialized, the .val method will
        // be called with the start options.
        parsed.start = entry;
    }

    function testSnap(parsed, entry) {
        // Enforce 100% stepping within subranges.
        parsed.snap = entry;

        if (typeof entry !== "boolean") {
            throw new Error("noUiSlider (" + VERSION + "): 'snap' option must be a boolean.");
        }
    }

    function testAnimate(parsed, entry) {
        // Enforce 100% stepping within subranges.
        parsed.animate = entry;

        if (typeof entry !== "boolean") {
            throw new Error("noUiSlider (" + VERSION + "): 'animate' option must be a boolean.");
        }
    }

    function testAnimationDuration(parsed, entry) {
        parsed.animationDuration = entry;

        if (typeof entry !== "number") {
            throw new Error("noUiSlider (" + VERSION + "): 'animationDuration' option must be a number.");
        }
    }

    function testConnect(parsed, entry) {
        var connect = [false];
        var i;

        // Map legacy options
        if (entry === "lower") {
            entry = [true, false];
        } else if (entry === "upper") {
            entry = [false, true];
        }

        // Handle boolean options
        if (entry === true || entry === false) {
            for (i = 1; i < parsed.handles; i++) {
                connect.push(entry);
            }

            connect.push(false);
        }

        // Reject invalid input
        else if (!Array.isArray(entry) || !entry.length || entry.length !== parsed.handles + 1) {
            throw new Error("noUiSlider (" + VERSION + "): 'connect' option doesn't match handle count.");
        } else {
            connect = entry;
        }

        parsed.connect = connect;
    }

    function testOrientation(parsed, entry) {
        // Set orientation to an a numerical value for easy
        // array selection.
        switch (entry) {
            case "horizontal":
                parsed.ort = 0;
                break;
            case "vertical":
                parsed.ort = 1;
                break;
            default:
                throw new Error("noUiSlider (" + VERSION + "): 'orientation' option is invalid.");
        }
    }

    function testMargin(parsed, entry) {
        if (!isNumeric(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'margin' option must be numeric.");
        }

        // Issue #582
        if (entry === 0) {
            return;
        }

        parsed.margin = parsed.spectrum.getDistance(entry);
    }

    function testLimit(parsed, entry) {
        if (!isNumeric(entry)) {
            throw new Error("noUiSlider (" + VERSION + "): 'limit' option must be numeric.");
        }

        parsed.limit = parsed.spectrum.getDistance(entry);

        if (!parsed.limit || parsed.handles < 2) {
            throw new Error(
                "noUiSlider (" +
                    VERSION +
                    "): 'limit' option is only supported on linear sliders with 2 or more handles."
            );
        }
    }

    function testPadding(parsed, entry) {
        var index;

        if (!isNumeric(entry) && !Array.isArray(entry)) {
            throw new Error(
                "noUiSlider (" + VERSION + "): 'padding' option must be numeric or array of exactly 2 numbers."
            );
        }

        if (Array.isArray(entry) && !(entry.length === 2 || isNumeric(entry[0]) || isNumeric(entry[1]))) {
            throw new Error(
                "noUiSlider (" + VERSION + "): 'padding' option must be numeric or array of exactly 2 numbers."
            );
        }

        if (entry === 0) {
            return;
        }

        if (!Array.isArray(entry)) {
            entry = [entry, entry];
        }

        // 'getDistance' returns false for invalid values.
        parsed.padding = [parsed.spectrum.getDistance(entry[0]), parsed.spectrum.getDistance(entry[1])];

        for (index = 0; index < parsed.spectrum.xNumSteps.length - 1; index++) {
            // last "range" can't contain step size as it is purely an endpoint.
            if (parsed.padding[0][index] < 0 || parsed.padding[1][index] < 0) {
                throw new Error("noUiSlider (" + VERSION + "): 'padding' option must be a positive number(s).");
            }
        }

        var totalPadding = entry[0] + entry[1];
        var firstValue = parsed.spectrum.xVal[0];
        var lastValue = parsed.spectrum.xVal[parsed.spectrum.xVal.length - 1];

        if (totalPadding / (lastValue - firstValue) > 1) {
            throw new Error("noUiSlider (" + VERSION + "): 'padding' option must not exceed 100% of the range.");
        }
    }

    function testDirection(parsed, entry) {
        // Set direction as a numerical value for easy parsing.
        // Invert connection for RTL sliders, so that the proper
        // handles get the connect/background classes.
        switch (entry) {
            case "ltr":
                parsed.dir = 0;
                break;
            case "rtl":
                parsed.dir = 1;
                break;
            default:
                throw new Error("noUiSlider (" + VERSION + "): 'direction' option was not recognized.");
        }
    }

    function testBehaviour(parsed, entry) {
        // Make sure the input is a string.
        if (typeof entry !== "string") {
            throw new Error("noUiSlider (" + VERSION + "): 'behaviour' must be a string containing options.");
        }

        // Check if the string contains any keywords.
        // None are required.
        var tap = entry.indexOf("tap") >= 0;
        var drag = entry.indexOf("drag") >= 0;
        var fixed = entry.indexOf("fixed") >= 0;
        var snap = entry.indexOf("snap") >= 0;
        var hover = entry.indexOf("hover") >= 0;
        var unconstrained = entry.indexOf("unconstrained") >= 0;

        if (fixed) {
            if (parsed.handles !== 2) {
                throw new Error("noUiSlider (" + VERSION + "): 'fixed' behaviour must be used with 2 handles");
            }

            // Use margin to enforce fixed state
            testMargin(parsed, parsed.start[1] - parsed.start[0]);
        }

        if (unconstrained && (parsed.margin || parsed.limit)) {
            throw new Error(
                "noUiSlider (" + VERSION + "): 'unconstrained' behaviour cannot be used with margin or limit"
            );
        }

        parsed.events = {
            tap: tap || snap,
            drag: drag,
            fixed: fixed,
            snap: snap,
            hover: hover,
            unconstrained: unconstrained
        };
    }

    function testTooltips(parsed, entry) {
        if (entry === false) {
            return;
        }

        if (entry === true) {
            parsed.tooltips = [];

            for (var i = 0; i < parsed.handles; i++) {
                parsed.tooltips.push(true);
            }
        } else {
            parsed.tooltips = asArray(entry);

            if (parsed.tooltips.length !== parsed.handles) {
                throw new Error("noUiSlider (" + VERSION + "): must pass a formatter for all handles.");
            }

            parsed.tooltips.forEach(function(formatter) {
                if (
                    typeof formatter !== "boolean" &&
                    (typeof formatter !== "object" || typeof formatter.to !== "function")
                ) {
                    throw new Error("noUiSlider (" + VERSION + "): 'tooltips' must be passed a formatter or 'false'.");
                }
            });
        }
    }

    function testAriaFormat(parsed, entry) {
        parsed.ariaFormat = entry;
        validateFormat(entry);
    }

    function testFormat(parsed, entry) {
        parsed.format = entry;
        validateFormat(entry);
    }

    function testKeyboardSupport(parsed, entry) {
        parsed.keyboardSupport = entry;

        if (typeof entry !== "boolean") {
            throw new Error("noUiSlider (" + VERSION + "): 'keyboardSupport' option must be a boolean.");
        }
    }

    function testDocumentElement(parsed, entry) {
        // This is an advanced option. Passed values are used without validation.
        parsed.documentElement = entry;
    }

    function testCssPrefix(parsed, entry) {
        if (typeof entry !== "string" && entry !== false) {
            throw new Error("noUiSlider (" + VERSION + "): 'cssPrefix' must be a string or `false`.");
        }

        parsed.cssPrefix = entry;
    }

    function testCssClasses(parsed, entry) {
        if (typeof entry !== "object") {
            throw new Error("noUiSlider (" + VERSION + "): 'cssClasses' must be an object.");
        }

        if (typeof parsed.cssPrefix === "string") {
            parsed.cssClasses = {};

            for (var key in entry) {
                if (!entry.hasOwnProperty(key)) {
                    continue;
                }

                parsed.cssClasses[key] = parsed.cssPrefix + entry[key];
            }
        } else {
            parsed.cssClasses = entry;
        }
    }

    // Test all developer settings and parse to assumption-safe values.
    function testOptions(options) {
        // To prove a fix for #537, freeze options here.
        // If the object is modified, an error will be thrown.
        // Object.freeze(options);

        var parsed = {
            margin: 0,
            limit: 0,
            padding: 0,
            animate: true,
            animationDuration: 300,
            ariaFormat: defaultFormatter,
            format: defaultFormatter