/**
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* @fileoverview Rule to flag for-in loops without if statements inside
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* @author Nicholas C. Zakas
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "require `for-in` loops to include an `if` statement",
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category: "Best Practices",
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recommended: false,
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url: "https://eslint.org/docs/rules/guard-for-in"
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},
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schema: [],
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messages: {
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wrap: "The body of a for-in should be wrapped in an if statement to filter unwanted properties from the prototype."
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}
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},
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create(context) {
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return {
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ForInStatement(node) {
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const body = node.body;
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// empty statement
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if (body.type === "EmptyStatement") {
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return;
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}
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// if statement
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if (body.type === "IfStatement") {
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return;
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}
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// empty block
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if (body.type === "BlockStatement" && body.body.length === 0) {
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return;
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}
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// block with just if statement
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if (body.type === "BlockStatement" && body.body.length === 1 && body.body[0].type === "IfStatement") {
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return;
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}
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// block that starts with if statement
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if (body.type === "BlockStatement" && body.body.length >= 1 && body.body[0].type === "IfStatement") {
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const i = body.body[0];
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// ... whose consequent is a continue
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if (i.consequent.type === "ContinueStatement") {
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return;
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}
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// ... whose consequent is a block that contains only a continue
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if (i.consequent.type === "BlockStatement" && i.consequent.body.length === 1 && i.consequent.body[0].type === "ContinueStatement") {
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return;
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}
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}
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context.report({ node, messageId: "wrap" });
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}
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};
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}
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};
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