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