Website Structure

Frontend-Learner/node_modules/eslint/lib/rules/guard-for-in.js

@@ -0,0 +1,85 @@
+/**
+ * @fileoverview Rule to flag for-in loops without if statements inside
+ * @author Nicholas C. Zakas
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../types').Rule.RuleModule} */
+module.exports = {
+	meta: {
+		type: "suggestion",
+
+		docs: {
+			description: "Require `for-in` loops to include an `if` statement",
+			recommended: false,
+			url: "https://eslint.org/docs/latest/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" });
+			},
+		};
+	},
+};