/** * @fileoverview Rule to flag when re-assigning native objects * @author Ilya Volodin */ "use strict"; //------------------------------------------------------------------------------ // Rule Definition //------------------------------------------------------------------------------ module.exports = function(context) { var config = context.options[0]; var exceptions = (config && config.exceptions) || []; /** * Gets the names of writeable built-in variables. * @param {escope.Scope} scope - A scope to get. * @returns {object} A map that its key is variable names. */ function getBuiltinGlobals(scope) { return scope.variables.reduce(function(retv, variable) { if (variable.writeable === false && variable.name !== "__proto__") { retv[variable.name] = true; } return retv; }, Object.create(null)); } /** * Reports if a given reference's name is same as native object's. * @param {object} builtins - A map that its key is a variable name. * @param {Reference} reference - A reference to check. * @param {int} index - The index of the reference in the references. * @param {Reference[]} references - The array that the reference belongs to. * @returns {void} */ function checkThroughReference(builtins, reference, index, references) { var identifier = reference.identifier; if (identifier && builtins[identifier.name] && exceptions.indexOf(identifier.name) === -1 && reference.init === false && reference.isWrite() && // Destructuring assignments can have multiple default value, // so possibly there are multiple writeable references for the same identifier. (index === 0 || references[index - 1].identifier !== identifier) ) { context.report( identifier, "{{name}} is a read-only native object.", {name: identifier.name}); } } return { // Checks assignments of global variables. // References to implicit global variables are not resolved, // so those are in the `through` of the global scope. "Program": function() { var globalScope = context.getScope(); var builtins = getBuiltinGlobals(globalScope); globalScope.through.forEach(checkThroughReference.bind(null, builtins)); } }; }; module.exports.schema = [ { "type": "object", "properties": { "exceptions": { "type": "array", "items": {"type": "string"}, "uniqueItems": true } }, "additionalProperties": false } ];