eslint/lib/rules/no-whitespace-before-property.js

/**
 * @fileoverview Rule to disallow whitespace before properties
 * @author Kai Cataldo
 */
"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const astUtils = require("./utils/ast-utils");

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

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

        docs: {
            description: "disallow whitespace before properties",
            category: "Stylistic Issues",
            recommended: false,
            url: "https://eslint.org/docs/rules/no-whitespace-before-property"
        },

        fixable: "whitespace",
        schema: [],

        messages: {
            unexpectedWhitespace: "Unexpected whitespace before property {{propName}}."
        }
    },

    create(context) {
        const sourceCode = context.getSourceCode();

        //--------------------------------------------------------------------------
        // Helpers
        //--------------------------------------------------------------------------

        /**
         * Reports whitespace before property token
         * @param {ASTNode} node the node to report in the event of an error
         * @param {Token} leftToken the left token
         * @param {Token} rightToken the right token
         * @returns {void}
         * @private
         */
        function reportError(node, leftToken, rightToken) {
            context.report({
                node,
                messageId: "unexpectedWhitespace",
                data: {
                    propName: sourceCode.getText(node.property)
                },
                fix(fixer) {
                    let replacementText = "";

                    if (!node.computed && !node.optional && astUtils.isDecimalInteger(node.object)) {

                        /*
                         * If the object is a number literal, fixing it to something like 5.toString() would cause a SyntaxError.
                         * Don't fix this case.
                         */
                        return null;
                    }

                    // Don't fix if comments exist.
                    if (sourceCode.commentsExistBetween(leftToken, rightToken)) {
                        return null;
                    }

                    if (node.optional) {
                        replacementText = "?.";
                    } else if (!node.computed) {
                        replacementText = ".";
                    }

                    return fixer.replaceTextRange([leftToken.range[1], rightToken.range[0]], replacementText);
                }
            });
        }

        //--------------------------------------------------------------------------
        // Public
        //--------------------------------------------------------------------------

        return {
            MemberExpression(node) {
                let rightToken;
                let leftToken;

                if (!astUtils.isTokenOnSameLine(node.object, node.property)) {
                    return;
                }

                if (node.computed) {
                    rightToken = sourceCode.getTokenBefore(node.property, astUtils.isOpeningBracketToken);
                    leftToken = sourceCode.getTokenBefore(rightToken, node.optional ? 1 : 0);
                } else {
                    rightToken = sourceCode.getFirstToken(node.property);
                    leftToken = sourceCode.getTokenBefore(rightToken, 1);
                }

                if (sourceCode.isSpaceBetweenTokens(leftToken, rightToken)) {
                    reportError(node, leftToken, rightToken);
                }
            }
        };
    }
};