no-useless-undefined: Ignore Set#add() Map#set() `Array#{push,u…

…nshift}()` (#1353)
sindresorhus · Jun 15, 2021 · c6359c3 · c6359c3
1 parent 4bf97a4
commit c6359c3
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Showing 2 changed files with 17 additions and 3 deletions.
diff --git a/rules/no-useless-undefined.js b/rules/no-useless-undefined.js
@@ -56,7 +56,7 @@ const compareFunctionNames = new Set([
 	'strictSame',
 	'strictNotSame'
 ]);
-const isCompareFunction = node => {
+const shouldIgnore = node => {
 	let name;
 
 	if (node.type === 'Identifier') {
@@ -70,7 +70,15 @@ const isCompareFunction = node => {
 		name = node.property.name;
 	}
 
-	return compareFunctionNames.has(name);
+	return compareFunctionNames.has(name) ||
+		// `set.add(undefined)`
+		name === 'add' ||
+		// `map.set(foo, undefined)`
+		name === 'set' ||
+		// `array.push(undefined)`
+		name === 'push' ||
+		// `array.unshift(undefined)`
+		name === 'unshift';
 };
 
 const getFunction = scope => {
@@ -126,7 +134,7 @@ const create = context => {
 
 	if (options.checkArguments) {
 		listeners.CallExpression = node => {
-			if (isCompareFunction(node.callee)) {
+			if (shouldIgnore(node.callee)) {
 				return;
 			}
 

diff --git a/test/no-useless-undefined.mjs b/test/no-useless-undefined.mjs
@@ -45,6 +45,12 @@ test({
 		't.strictSame(foo, undefined)',
 		't.strictNotSame(foo, undefined)',
 		'expect(someFunction).toHaveBeenCalledWith(1, 2, undefined);',
+		'set.add(undefined);',
+		'map.set(foo, undefined);',
+		'array.push(foo, undefined);',
+		'array.push(undefined);',
+		'array.unshift(foo, undefined);',
+		'array.unshift(undefined);',
 
 		// `checkArguments: false`
 		{