Add timeout option (sindresorhus#21)

fregante · sindresorhus · commit 5bd3ad455a17 · 2019-05-28T11:27:58.000+07:00
diff --git a/index.d.ts b/index.d.ts
@@ -9,6 +9,13 @@ declare namespace elementReady {
 		*/
 		readonly target?: Element | Document;
 
+		/**
+		Milliseconds to wait before stopping the search and resolving the promise to `undefined`.
+
+		@default Infinity
+		*/
+		readonly timeout?: number
+
 		/**
 		Automatically stop checking for the element to be ready after the DOM ready event. The promise is then resolved to `undefined`.
 
diff --git a/index.js b/index.js
@@ -5,13 +5,12 @@ const pDefer = require('p-defer');
 
 const cache = new ManyKeysMap();
 
-const elementReady = (selector, options = {}) => {
-	const {
-		target = document,
-		stopOnDomReady = true
-	} = options;
-
-	const cacheKeys = [target, selector, stopOnDomReady];
+const elementReady = (selector, {
+	target = document,
+	stopOnDomReady = true,
+	timeout = Infinity
+} = {}) => {
+	const cacheKeys = [target, selector, stopOnDomReady, timeout];
 	const cachedPromise = cache.get(cacheKeys);
 	if (cachedPromise) {
 		return cachedPromise;
@@ -36,6 +35,10 @@ const elementReady = (selector, options = {}) => {
 		})();
 	}
 
+	if (timeout !== Infinity) {
+		setTimeout(stop, timeout);
+	}
+
 	// Interval to keep checking for it to come into the DOM
 	(function check() {
 		const element = target.querySelector(selector);
diff --git a/index.test-d.ts b/index.test-d.ts
@@ -4,6 +4,7 @@ import elementReady = require('.');
 const promise = elementReady('#unicorn');
 elementReady('#unicorn', {target: document});
 elementReady('#unicorn', {target: document.documentElement});
+elementReady('#unicorn', {timeout: 1000000});
 
 elementReady('#unicorn', {stopOnDomReady: false});
 
diff --git a/readme.md b/readme.md
@@ -54,6 +54,13 @@ Default: `true`
 
 Automatically stop checking for the element to be ready after the [DOM ready event](https://developer.mozilla.org/en-US/docs/Web/API/Window/DOMContentLoaded_event). The promise is then resolved to `undefined`.
 
+##### timeout
+
+Type: `number`<br>
+Default: `Infinity`
+
+Milliseconds to wait before stopping the search and resolving the promise to `undefined`.
+
 ### elementReadyPromise#stop()
 
 Type: `Function`
diff --git a/test.js b/test.js
@@ -103,6 +103,36 @@ test('check if element ready before dom loaded', async t => {
 	t.is(await elementCheck, element);
 });
 
+test('check if element ready after timeout', async t => {
+	const elementCheck = elementReady('#cheezburger', {
+		stopOnDomReady: false,
+		timeout: 1000
+	});
+
+	// The element will be added eventually, but we're not around to wait for it
+	setTimeout(() => {
+		const element = document.createElement('p');
+		element.id = 'cheezburger';
+		document.body.append(element);
+	}, 50000);
+
+	const element = await elementCheck;
+	t.is(element, undefined);
+});
+
+test('check if element ready before timeout', async t => {
+	const element = document.createElement('p');
+	element.id = 'thunders';
+	document.body.append(element);
+
+	const elementCheck = elementReady('#thunders', {
+		stopOnDomReady: false,
+		timeout: 10
+	});
+
+	t.is(await elementCheck, element);
+});
+
 test('ensure only one promise is returned on multiple calls passing the same selector', t => {
 	const elementCheck = elementReady('#not-found', {stopOnDomReady: false});
 
