noVarKeywordRule.js 4.3KB

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  1. "use strict";
  2. /**
  3. * @license
  4. * Copyright 2015 Palantir Technologies, Inc.
  5. *
  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
  9. *
  10. * http://www.apache.org/licenses/LICENSE-2.0
  11. *
  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.
  17. */
  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);
  25. function Rule() {
  26. return _super !== null && _super.apply(this, arguments) || this;
  27. }
  28. Rule.prototype.apply = function (sourceFile) {
  29. return this.applyWithFunction(sourceFile, walk);
  30. };
  31. /* tslint:disable:object-literal-sort-keys */
  32. Rule.metadata = {
  33. ruleName: "no-var-keyword",
  34. description: "Disallows usage of the `var` keyword.",
  35. descriptionDetails: "Use `let` or `const` instead.",
  36. hasFix: true,
  37. optionsDescription: "Not configurable.",
  38. options: null,
  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,
  43. };
  44. /* tslint:enable:object-literal-sort-keys */
  45. Rule.FAILURE_STRING = "Forbidden 'var' keyword, use 'let' or 'const' instead";
  46. return Rule;
  47. }(Lint.Rules.AbstractRule));
  48. exports.Rule = Rule;
  49. function walk(ctx) {
  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 ? undefined : new Lint.Replacement(start, width, "let");
  61. ctx.addFailureAt(start, width, Rule.FAILURE_STRING, fix);
  62. }
  63. return ts.forEachChild(node, cb);
  64. });
  65. }
  66. // Allow `declare var x: number;` or `declare global { var x: number; }`
  67. function isGlobalVarDeclaration(node) {
  68. var parent = node.parent;
  69. return tsutils_1.hasModifier(node.modifiers, ts.SyntaxKind.DeclareKeyword)
  70. || parent.kind === ts.SyntaxKind.ModuleBlock && tsutils_1.isNodeFlagSet(parent.parent, ts.NodeFlags.GlobalAugmentation);
  71. }
  72. var templateObject_1;