4 * Copyright 2015 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 Rule = /** @class */ (function (_super) {
24 tslib_1.__extends(Rule, _super);
26 return _super !== null && _super.apply(this, arguments) || this;
28 Rule.prototype.apply = function (sourceFile) {
29 return this.applyWithFunction(sourceFile, walk);
31 /* tslint:disable:object-literal-sort-keys */
33 ruleName: "no-var-keyword",
34 description: "Disallows usage of the `var` keyword.",
35 descriptionDetails: "Use `let` or `const` instead.",
37 optionsDescription: "Not configurable.",
39 optionExamples: [true],
40 rationale: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n Declaring variables using `var` has several edge case behaviors that make `var` unsuitable for modern code.\n Variables declared by `var` have their parent function block as their scope, ignoring other control flow statements.\n `var`s have declaration \"hoisting\" (similar to `function`s) and can appear to be used before declaration.\n\n Variables declared by `const` and `let` instead have as their scope the block in which they are defined,\n and are not allowed to used before declaration or be re-declared with another `const` or `let`.\n "], ["\n Declaring variables using \\`var\\` has several edge case behaviors that make \\`var\\` unsuitable for modern code.\n Variables declared by \\`var\\` have their parent function block as their scope, ignoring other control flow statements.\n \\`var\\`s have declaration \"hoisting\" (similar to \\`function\\`s) and can appear to be used before declaration.\n\n Variables declared by \\`const\\` and \\`let\\` instead have as their scope the block in which they are defined,\n and are not allowed to used before declaration or be re-declared with another \\`const\\` or \\`let\\`.\n "]))),
41 type: "functionality",
42 typescriptOnly: false,
44 /* tslint:enable:object-literal-sort-keys */
45 Rule.FAILURE_STRING = "Forbidden 'var' keyword, use 'let' or 'const' instead";
47 }(Lint.Rules.AbstractRule));
50 var sourceFile = ctx.sourceFile;
51 return ts.forEachChild(sourceFile, function cb(node) {
52 var parent = node.parent;
53 if (tsutils_1.isVariableDeclarationList(node) &&
54 !tsutils_1.isBlockScopedVariableDeclarationList(node) &&
55 // If !isVariableStatement, this is inside of a for loop.
56 (!tsutils_1.isVariableStatement(parent) || !isGlobalVarDeclaration(parent))) {
57 var start = node.getStart(sourceFile);
58 var width = "var".length;
59 // Don't apply fix in a declaration file, because may have meant 'const'.
60 var fix = sourceFile.isDeclarationFile
62 : new Lint.Replacement(start, width, "let");
63 ctx.addFailureAt(start, width, Rule.FAILURE_STRING, fix);
65 return ts.forEachChild(node, cb);
68 // Allow `declare var x: number;` or `declare global { var x: number; }`
69 function isGlobalVarDeclaration(node) {
70 var parent = node.parent;
71 return (tsutils_1.hasModifier(node.modifiers, ts.SyntaxKind.DeclareKeyword) ||
72 (parent.kind === ts.SyntaxKind.ModuleBlock &&
73 tsutils_1.isNodeFlagSet(parent.parent, ts.NodeFlags.GlobalAugmentation)));