4 * Copyright 2013 Palantir Technologies, Inc.
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
10 * http://www.apache.org/licenses/LICENSE-2.0
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
18 Object.defineProperty(exports, "__esModule", { value: true });
19 var tslib_1 = require("tslib");
20 var tsutils_1 = require("tsutils");
21 var ts = require("typescript");
22 var Lint = require("../index");
23 var useIsnan_examples_1 = require("./code-examples/useIsnan.examples");
24 var Rule = /** @class */ (function (_super) {
25 tslib_1.__extends(Rule, _super);
27 return _super !== null && _super.apply(this, arguments) || this;
29 Rule.prototype.apply = function (sourceFile) {
30 return this.applyWithFunction(sourceFile, walk);
32 /* tslint:disable:object-literal-sort-keys */
34 ruleName: "use-isnan",
35 description: "Enforces use of the `isNaN()` function to check for NaN references instead of a comparison to the `NaN` constant.",
36 rationale: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n Since `NaN !== NaN`, comparisons with regular operators will produce unexpected results.\n So, instead of `if (myVar === NaN)`, do `if (isNaN(myVar))`."], ["\n Since \\`NaN !== NaN\\`, comparisons with regular operators will produce unexpected results.\n So, instead of \\`if (myVar === NaN)\\`, do \\`if (isNaN(myVar))\\`."]))),
37 optionsDescription: "Not configurable.",
39 optionExamples: [true],
40 type: "functionality",
41 typescriptOnly: false,
42 codeExamples: useIsnan_examples_1.codeExamples,
44 /* tslint:enable:object-literal-sort-keys */
45 Rule.FAILURE_STRING = "Found an invalid comparison for NaN: ";
47 }(Lint.Rules.AbstractRule));
50 return ts.forEachChild(ctx.sourceFile, function cb(node) {
51 if (tsutils_1.isBinaryExpression(node)) {
52 switch (node.operatorToken.kind) {
53 case ts.SyntaxKind.LessThanToken:
54 case ts.SyntaxKind.GreaterThanToken:
55 case ts.SyntaxKind.LessThanEqualsToken:
56 case ts.SyntaxKind.GreaterThanEqualsToken:
57 case ts.SyntaxKind.EqualsEqualsToken:
58 case ts.SyntaxKind.ExclamationEqualsToken:
59 case ts.SyntaxKind.EqualsEqualsEqualsToken:
60 case ts.SyntaxKind.ExclamationEqualsEqualsToken:
61 if (isExpressionNaN(node.right) || isExpressionNaN(node.left)) {
62 ctx.addFailureAtNode(node, Rule.FAILURE_STRING + node.getText(ctx.sourceFile));
66 return ts.forEachChild(node, cb);
69 function isExpressionNaN(node) {
70 return node.kind === ts.SyntaxKind.Identifier && node.text === "NaN";