noForInArrayRule.js
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"use strict";
var __extends = (this && this.__extends) || function (d, b) {
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var ts = require("typescript");
var Lint = require("../lint");
var Rule = (function (_super) {
__extends(Rule, _super);
function Rule() {
_super.apply(this, arguments);
}
Rule.prototype.applyWithProgram = function (sourceFile, program) {
var noForInArrayWalker = new NoForInArrayWalker(sourceFile, this.getOptions(), program);
return this.applyWithWalker(noForInArrayWalker);
};
Rule.metadata = {
ruleName: "no-for-in-array",
description: "Disallows iterating over an array with a for-in loop.",
descriptionDetails: (_a = ["\n A for-in loop (`for (var k in o)`) iterates over the properties of an Object.\n\n While it is legal to use for-in loops with array types, it is not common.\n for-in will iterate over the indices of the array as strings, omitting any \"holes\" in\n the array.\n\n More common is to use for-of, which iterates over the values of an array.\n If you want to iterate over the indices, alternatives include:\n\n array.forEach((value, index) => { ... });\n for (const [index, value] of array.entries()) { ... }\n for (let i = 0; i < array.length; i++) { ... }\n "], _a.raw = ["\n A for-in loop (\\`for (var k in o)\\`) iterates over the properties of an Object.\n\n While it is legal to use for-in loops with array types, it is not common.\n for-in will iterate over the indices of the array as strings, omitting any \"holes\" in\n the array.\n\n More common is to use for-of, which iterates over the values of an array.\n If you want to iterate over the indices, alternatives include:\n\n array.forEach((value, index) => { ... });\n for (const [index, value] of array.entries()) { ... }\n for (let i = 0; i < array.length; i++) { ... }\n "], Lint.Utils.dedent(_a)),
optionsDescription: "Not configurable.",
options: null,
optionExamples: ["true"],
requiresTypeInfo: true,
type: "functionality",
};
Rule.FAILURE_STRING = "for-in loops over arrays are forbidden. Use for-of or array.forEach instead.";
return Rule;
var _a;
}(Lint.Rules.TypedRule));
exports.Rule = Rule;
var NoForInArrayWalker = (function (_super) {
__extends(NoForInArrayWalker, _super);
function NoForInArrayWalker() {
_super.apply(this, arguments);
}
NoForInArrayWalker.prototype.visitForInStatement = function (node) {
var iteratee = node.expression;
var tc = this.getTypeChecker();
var type = tc.getTypeAtLocation(iteratee);
var isArrayType = type.symbol && type.symbol.name === "Array";
var isStringType = (type.flags & ts.TypeFlags.StringLike) !== 0;
if (isArrayType || isStringType) {
this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.FAILURE_STRING));
}
_super.prototype.visitForInStatement.call(this, node);
};
return NoForInArrayWalker;
}(Lint.ProgramAwareRuleWalker));