banCommaOperatorRule.js 3.9 KB

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  1. "use strict";
  2. /**
  3. * @license
  4. * Copyright 2017 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 max-line-length */
  32. Rule.metadata = {
  33. ruleName: "ban-comma-operator",
  34. description: "Disallows the comma operator to be used.",
  35. descriptionDetails: "[Read more about the comma operator here](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Comma_Operator).",
  36. rationale: Lint.Utils.dedent(templateObject_1 || (templateObject_1 = tslib_1.__makeTemplateObject(["\n Using the comma operator can create a potential for many non-obvious bugs or lead to misunderstanding of code.\n\n ### Examples\n ```\n foo((bar, baz)); // evaluates to 'foo(baz)' because of the extra parens - confusing and not obvious\n ```\n\n ```\n switch (foo) {\n case 1, 2: // equals 'case 2' - probably intended 'case 1: case2:'\n return true;\n case 3:\n return false;\n }\n ```\n\n ```\n let x = (y = 1, z = 2); // x is equal to 2 - this may not be immediately obvious.\n ```\n "], ["\n Using the comma operator can create a potential for many non-obvious bugs or lead to misunderstanding of code.\n\n ### Examples\n \\`\\`\\`\n foo((bar, baz)); // evaluates to 'foo(baz)' because of the extra parens - confusing and not obvious\n \\`\\`\\`\n\n \\`\\`\\`\n switch (foo) {\n case 1, 2: // equals 'case 2' - probably intended 'case 1: case2:'\n return true;\n case 3:\n return false;\n }\n \\`\\`\\`\n\n \\`\\`\\`\n let x = (y = 1, z = 2); // x is equal to 2 - this may not be immediately obvious.\n \\`\\`\\`\n "]))),
  37. options: null,
  38. optionsDescription: "",
  39. optionExamples: [true],
  40. type: "functionality",
  41. typescriptOnly: false,
  42. };
  43. /* tslint:enable:object-literal-sort-keys max-line-length */
  44. Rule.FAILURE_STRING = "Do not use comma operator here because it can be easily misunderstood or lead to unintended bugs.";
  45. return Rule;
  46. }(Lint.Rules.AbstractRule));
  47. exports.Rule = Rule;
  48. function walk(ctx) {
  49. return ts.forEachChild(ctx.sourceFile, function cb(node) {
  50. if (tsutils_1.isBinaryExpression(node) && node.operatorToken.kind === ts.SyntaxKind.CommaToken && !isForLoopIncrementor(node)) {
  51. ctx.addFailureAtNode(node, Rule.FAILURE_STRING);
  52. }
  53. return ts.forEachChild(node, cb);
  54. });
  55. }
  56. function isForLoopIncrementor(node) {
  57. var parent = node.parent;
  58. return parent.kind === ts.SyntaxKind.ForStatement && parent.incrementor === node;
  59. }
  60. var templateObject_1;