eslint/lib/rules/quote-props.js

/**
 * @fileoverview Rule to flag non-quoted property names in object literals.
 * @author Mathias Bynens <http://mathiasbynens.be/>
 * @copyright 2014 Brandon Mills. All rights reserved.
 * @copyright 2015 Tomasz Olędzki. All rights reserved.
 */
"use strict";

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

var espree = require("espree"),
    keywords = require("../util/keywords");

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

module.exports = function(context) {

    var MODE = context.options[0],
        KEYWORDS = context.options[1] && context.options[1].keywords,
        CHECK_UNNECESSARY = !context.options[1] || context.options[1].unnecessary !== false,
        NUMBERS = context.options[1] && context.options[1].numbers,

        MESSAGE_UNNECESSARY = "Unnecessarily quoted property '{{property}}' found.",
        MESSAGE_UNQUOTED = "Unquoted property '{{property}}' found.",
        MESSAGE_NUMERIC = "Unquoted number literal '{{property}}' used as key.",
        MESSAGE_RESERVED = "Unquoted reserved word '{{property}}' used as key.";


    /**
     * Checks whether a certain string constitutes an ES3 token
     * @param   {string} tokenStr - The string to be checked.
     * @returns {boolean} `true` if it is an ES3 token.
     */
    function isKeyword(tokenStr) {
        return keywords.indexOf(tokenStr) >= 0;
    }

    /**
     * Checks if an espree-tokenized key has redundant quotes (i.e. whether quotes are unnecessary)
     * @param   {espreeTokens} tokens The espree-tokenized node key
     * @param   {boolean} [skipNumberLiterals=false] Indicates whether number literals should be checked
     * @returns {boolean} Whether or not a key has redundant quotes.
     * @private
     */
    function areQuotesRedundant(tokens, skipNumberLiterals) {
        return tokens.length === 1 &&
            (["Identifier", "Keyword", "Null", "Boolean"].indexOf(tokens[0].type) >= 0 ||
            (tokens[0].type === "Numeric" && !skipNumberLiterals && "" + +tokens[0].value === tokens[0].value));
    }

    /**
     * Ensures that a property's key is quoted only when necessary
     * @param   {ASTNode} node Property AST node
     * @returns {void}
     */
    function checkUnnecessaryQuotes(node) {
        var key = node.key,
            isKeywordToken,
            tokens;

        if (node.method || node.computed || node.shorthand) {
            return;
        }

        if (key.type === "Literal" && typeof key.value === "string") {
            try {
                tokens = espree.tokenize(key.value);
            } catch (e) {
                return;
            }

            if (tokens.length !== 1) {
                return;
            }

            isKeywordToken = isKeyword(tokens[0].value);

            if (isKeywordToken && KEYWORDS) {
                return;
            }

            if (CHECK_UNNECESSARY && areQuotesRedundant(tokens, NUMBERS)) {
                context.report(node, MESSAGE_UNNECESSARY, {property: key.value});
            }
        } else if (KEYWORDS && key.type === "Identifier" && isKeyword(key.name)) {
            context.report(node, MESSAGE_RESERVED, {property: key.name});
        } else if (NUMBERS && key.type === "Literal" && typeof key.value === "number") {
            context.report(node, MESSAGE_NUMERIC, {property: key.value});
        }
    }

    /**
     * Ensures that a property's key is quoted
     * @param   {ASTNode} node Property AST node
     * @returns {void}
     */
    function checkOmittedQuotes(node) {
        var key = node.key;

        if (!node.method && !node.computed && !node.shorthand && !(key.type === "Literal" && typeof key.value === "string")) {
            context.report(node, MESSAGE_UNQUOTED, {
                property: key.name || key.value
            });
        }
    }

    /**
     * Ensures that an object's keys are consistently quoted, optionally checks for redundancy of quotes
     * @param   {ASTNode} node Property AST node
     * @param   {boolean} checkQuotesRedundancy Whether to check quotes' redundancy
     * @returns {void}
     */
    function checkConsistency(node, checkQuotesRedundancy) {
        var quotes = false,
            lackOfQuotes = false,
            necessaryQuotes = false;

        node.properties.forEach(function(property) {
            var key = property.key,
                tokens;

            if (!key || property.method || property.computed || property.shorthand) {
                return;
            }

            if (key.type === "Literal" && typeof key.value === "string") {

                quotes = true;

                if (checkQuotesRedundancy) {
                    try {
                        tokens = espree.tokenize(key.value);
                    } catch (e) {
                        necessaryQuotes = true;
                        return;
                    }

                    necessaryQuotes = necessaryQuotes || !areQuotesRedundant(tokens) || KEYWORDS && isKeyword(tokens[0].value);
                }
            } else if (KEYWORDS && checkQuotesRedundancy && key.type === "Identifier" && isKeyword(key.name)) {
                necessaryQuotes = true;
                context.report(node, "Properties should be quoted as '{{property}}' is a reserved word.", {property: key.name});
            } else {
                lackOfQuotes = true;
            }

            if (quotes && lackOfQuotes) {
                context.report(node, "Inconsistently quoted property '{{key}}' found.", {
                    key: key.name || key.value
                });
            }
        });

        if (checkQuotesRedundancy && quotes && !necessaryQuotes) {
            context.report(node, "Properties shouldn't be quoted as all quotes are redundant.");
        }
    }

    return {
        "Property": function(node) {
            if (MODE === "always" || !MODE) {
                checkOmittedQuotes(node);
            }
            if (MODE === "as-needed") {
                checkUnnecessaryQuotes(node);
            }
        },
        "ObjectExpression": function(node) {
            if (MODE === "consistent") {
                checkConsistency(node, false);
            }
            if (MODE === "consistent-as-needed") {
                checkConsistency(node, true);
            }
        }
    };

};

module.exports.schema = {
    "anyOf": [
        {
            "type": "array",
            "items": [
                {
                    "enum": ["always", "as-needed", "consistent", "consistent-as-needed"]
                }
            ],
            "minItems": 0,
            "maxItems": 1
        },
        {
            "type": "array",
            "items": [
                {
                    "enum": ["always", "as-needed", "consistent", "consistent-as-needed"]
                },
                {
                    "type": "object",
                    "properties": {
                        "keywords": {
                            "type": "boolean"
                        },
                        "unnecessary": {
                            "type": "boolean"
                        },
                        "numbers": {
                            "type": "boolean"
                        }
                    },
                    "additionalProperties": false
                }
            ],
            "minItems": 0,
            "maxItems": 2
        }
    ]
};