tslint/lib/rules/typeofCompareRule.js

An extensible static analysis linter for the TypeScript language

"use strict";
/**
 * @license
 * Copyright 2013 Palantir Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.Rule = void 0;
var tslib_1 = require("tslib");
var tsutils = require("tsutils");
var ts = require("typescript");
var Lint = require("../index");
var LEGAL_TYPEOF_RESULTS = new Set([
    "undefined",
    "string",
    "boolean",
    "number",
    "function",
    "object",
    "symbol",
]);
var Rule = /** @class */ (function (_super) {
    tslib_1.__extends(Rule, _super);
    function Rule() {
        return _super !== null && _super.apply(this, arguments) || this;
    }
    Rule.prototype.apply = function (sourceFile) {
        return this.applyWithFunction(sourceFile, walk);
    };
    /* tslint:disable:object-literal-sort-keys */
    Rule.metadata = {
        ruleName: "typeof-compare",
        description: "Makes sure result of `typeof` is compared to correct string values",
        optionsDescription: "Not configurable.",
        options: null,
        optionExamples: [true],
        type: "functionality",
        typescriptOnly: false,
        deprecationMessage: !/^2\.1\./.test(ts.version)
            ? "Starting from TypeScript 2.2 the compiler includes this check which makes this rule redundant."
            : "",
    };
    /* tslint:enable:object-literal-sort-keys */
    Rule.FAILURE_STRING = "'typeof' expression must be compared to one of: " + Array.from(LEGAL_TYPEOF_RESULTS)
        .map(function (x) { return "\"" + x + "\""; })
        .join(", ");
    return Rule;
}(Lint.Rules.AbstractRule));
exports.Rule = Rule;
function walk(ctx) {
    ts.forEachChild(ctx.sourceFile, function cb(node) {
        if (tsutils.isBinaryExpression(node)) {
            var operatorToken = node.operatorToken, left = node.left, right = node.right;
            if (Lint.getEqualsKind(operatorToken) !== undefined &&
                (isFaultyTypeof(left, right) || isFaultyTypeof(right, left))) {
                ctx.addFailureAtNode(node, Rule.FAILURE_STRING);
            }
        }
        ts.forEachChild(node, cb);
    });
}
function isFaultyTypeof(left, right) {
    return left.kind === ts.SyntaxKind.TypeOfExpression && isFaultyTypeofResult(right);
}
function isFaultyTypeofResult(node) {
    switch (node.kind) {
        case ts.SyntaxKind.StringLiteral:
            return !LEGAL_TYPEOF_RESULTS.has(node.text);
        case ts.SyntaxKind.Identifier:
            return node.originalKeywordKind === ts.SyntaxKind.UndefinedKeyword;
        case ts.SyntaxKind.NullKeyword:
        case ts.SyntaxKind.NumericLiteral:
        case ts.SyntaxKind.TrueKeyword:
        case ts.SyntaxKind.FalseKeyword:
        case ts.SyntaxKind.ObjectLiteralExpression:
        case ts.SyntaxKind.ArrayLiteralExpression:
            return true;
        default:
            return false;
    }
}