object-property-newline.js

/**
 * @fileoverview Rule to enforce placing object properties on separate lines.
 * @author Vitor Balocco
 */

"use strict";

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = {
    meta: {
        type: "layout",

        docs: {
            description: "enforce placing object properties on separate lines",
            category: "Stylistic Issues",
            recommended: false,
            url: "https://eslint.org/docs/rules/object-property-newline"
        },

        schema: [
            {
                type: "object",
                properties: {
                    allowAllPropertiesOnSameLine: {
                        type: "boolean",
                        default: false
                    },
                    allowMultiplePropertiesPerLine: { // Deprecated
                        type: "boolean",
                        default: false
                    }
                },
                additionalProperties: false
            }
        ],

        fixable: "whitespace",

        messages: {
            propertiesOnNewlineAll: "Object properties must go on a new line if they aren't all on the same line.",
            propertiesOnNewline: "Object properties must go on a new line."
        }
    },

    create(context) {
        const allowSameLine = context.options[0] && (
            (context.options[0].allowAllPropertiesOnSameLine || context.options[0].allowMultiplePropertiesPerLine /* Deprecated */)
        );
        const messageId = allowSameLine
            ? "propertiesOnNewlineAll"
            : "propertiesOnNewline";

        const sourceCode = context.getSourceCode();

        return {
            ObjectExpression(node) {
                if (allowSameLine) {
                    if (node.properties.length > 1) {
                        const firstTokenOfFirstProperty = sourceCode.getFirstToken(node.properties[0]);
                        const lastTokenOfLastProperty = sourceCode.getLastToken(node.properties[node.properties.length - 1]);

                        if (firstTokenOfFirstProperty.loc.end.line === lastTokenOfLastProperty.loc.start.line) {

                            // All keys and values are on the same line
                            return;
                        }
                    }