no-array-constructor.js

/**
 * @fileoverview Disallow construction of dense arrays using the Array constructor
 * @author Matt DuVall <http://www.mattduvall.com/>
 */

"use strict";

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

const {
    getVariableByName,
    isClosingParenToken,
    isOpeningParenToken,
    isStartOfExpressionStatement,
    needsPrecedingSemicolon
} = require("./utils/ast-utils");

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

/** @type {import('../shared/types').Rule} */
module.exports = {
    meta: {
        type: "suggestion",

        docs: {
            description: "Disallow `Array` constructors",
            recommended: false,
            url: "https://eslint.org/docs/latest/rules/no-array-constructor"
        },

        hasSuggestions: true,

        schema: [],

        messages: {
            preferLiteral: "The array literal notation [] is preferable.",
            useLiteral: "Replace with an array literal.",
            useLiteralAfterSemicolon: "Replace with an array literal, add preceding semicolon."
        }
    },

    create(context) {

        const sourceCode = context.sourceCode;

        /**
         * Gets the text between the calling parentheses of a CallExpression or NewExpression.
         * @param {ASTNode} node A CallExpression or NewExpression node.
         * @returns {string} The text between the calling parentheses, or an empty string if there are none.
         */
        function getArgumentsText(node) {
            const lastToken = sourceCode.getLastToken(node);

            if (!isClosingParenToken(lastToken)) {
                return "";
            }

            let firstToken = node.callee;

            do {
                firstToken = sourceCode.getTokenAfter(firstToken);
                if (!firstToken || firstToken === lastToken) {
                    return "";
                }
            } while (!isOpeningParenToken(firstToken));

            return sourceCode.text.slice(firstToken.range[1], lastToken.range[0]);
        }

        /**
         * Disallow construction of dense arrays using the Array constructor
         * @param {ASTNode} node node to evaluate
         * @returns {void}
         * @private
         */
        function check(node) {
            if (
                node.callee.type !== "Identifier" ||
                node.callee.name !== "Array" ||
                node.arguments.length === 1 &&
                node.arguments[0].type !== "SpreadElement") {
                return;
            }

            const variable = getVariableByName(sourceCode.getScope(node), "Array");

            /*
             * Check if `Array` is a predefined global variable: predefined globals have no declarations,
             * meaning that the `identifiers` list of the variable object is empty.
             */
            if (variable && variable.identifiers.length === 0) {
                const argsText = getArgumentsText(node);
                let fixText;
                let messageId;

                /*
                 * Check if the suggested change should include a preceding semicolon or not.
                 * Due to JavaScript's ASI rules, a missing semicolon may be inserted automatically
                 * before an expression like `Array()` or `new Array()`, but not when the expression
                 * is changed into an array literal like `[]`.
                 */
                if (isStartOfExpressionStatement(node) && needsPrecedingSemicolon(sourceCode, node)) {
                    fixText = `;[${argsText}]`;
                    messageId = "useLiteralAfterSemicolon";
                } else {
                    fixText = `[${argsText}]`;
                    messageId = "useLiteral";
                }

                context.report({
                    node,
                    messageId: "preferLiteral",
                    suggest: [
                        {
                            messageId,
                            fix: fixer => fixer.replaceText(node, fixText)
                        }
                    ]
                });
            }
        }

        return {
            CallExpression: check,
            NewExpression: check
        };

    }
};