Document queryselector returns null querySelector() 将返回与指定的选择器组匹配的第一个元素。如果没有找到匹配项，则返回“null”。 语法： let input = document. querySelector returns null on lines 37 and 38 (I've marked these lines in the code so you don't have to look for them), when pressed for the first time, and then returns the desired value I was facing the same problem and now it is resolved by using var canvas=document. querySelector返回null但元素存在. querySelectorAll('. href). wrap your code in a addEventListener('load', => { /* your code */ });, but if the site is constructing the page dynamically after load, it won't help. The title should give a proper summary of the actual problem and not a "might describe the situation good enough" – Sep 6, 2021 · If you want to detect when an element appears then you need to either: Listen for mutations to the DOM; Poll (e. Googled and found out about "run_at": "document_end" and added it in my manifest file but my console. querySelector放在window. querySelector method in React. querySelector() 方法将返回 null。 Aug 27, 2020 · The approach I took to solve this issue is as follows: // using an IIFE ("Immediately-Invoked Function Expression"): (function() { 'use strict'; // using Arrow function syntax to define the callback function // supplied to the (later-created) mutation observer, with // two arguments (supplied automatically by that mutation // observer), the first 'mutationList' is an Array of // MutationRecord Mar 3, 2024 · To solve the "Cannot read property 'querySelector' of null" error, make sure you're using the correct `id` when selecting the DOM element. some-class') may return null. Mar 16, 2025 · Returns a single element object or null if no match is found. head. querySelector() returns null. Aug 9, 2024 · I have issues selecting certain elements on a specific web page, querySelector returns null unless I first go through one of the parent element. reduce your webpage by removing bits at a time until you're either left with just that element and things still don't work, or at some point you remove something and suddenly your code does work. May 2, 2023 · console. In Firefox this returns a NULL. box'); Instead, you should move the JS script tag to the bottom of the body, after the elements it tries to access. The matching is done using depth-first pre-order traversal of the document's nodes starting with the first element in the document's markup and iterating May 15, 2021 · "Document query selector returns undefined" (which won't ever be the case) but then "Type Error: Can not read property ClassList Of Null". Both have a length property that returns the number of elements in the list (collection). querySelector call inside the DOMContentLoaded event handler. returns an undefined Mar 5, 2024 · If neither element is found, the querySelector() method returns null. An HTMLCollection is a collection of document elements. querySelector("canvas"); instead of var canvas=document. querySelector('[data-testid="AddToCartButton"]') null > container. forEach. hello') // will return null Also, note that you don't need to pass # in this function argument. querySelector(". offsetWidth In google chrome this returns the width of a the text element which is nested inside an a (anchor) element which is nested inside an svg element, as is expected. querySelector. call`の挙動について学習中ですが、 以下のコードで `document. I'm already despera Aug 2, 2021 · The querySelector method returns Element | null. — You are receiving this because you are subscribed to this thread. styleSheet = document. The Document method querySelector() returns the first Element within the document that matches the specified selector, or group of selectors. So how should we prevent errors with querySelectorAll?Previously I would use instanceof to check if my variable was a NodeList, but this doesn’t work because querySelectorAll always returns a NodeList. Expressions can't be passed between the page and the Node script without careful considerations: most importantly, if something isn't serializable (converted into plain JSON), it can't be transferred. # Check if a DOM element exists using getElementsByClassName. Please note that the querySelector() method returns a single matching element, whereas the querySelectorAll() method returns a list of all matching elements. price'); should be return document. Use page. If you're not using strictNullChecks then Element, and it doesn't have the value member. querySelector('main'), and line becomes const mainElement = document. Aug 19, 2019 · tableBody = document. The issue is that you are attempting to access a property of a null value (null. You can't access class by doing something like. Aug 25, 2024 · This is my first time trying to make a Chrome extension. supplier-data'); } Then in the render method I call another file which calls another file which calls another file which has the following in its render method: I'm trying to build a chrome extension for Vimeo but I don't understand why document. document. A Sep 23, 2017 · In other words, you cannot return an element from the page DOM environment back to the Node. querySelector('SVG > a:nth-child(2) > text'). Feb 14, 2024 · Handling Null Values. querySelector("canvas"); is getting the element from tag name canvas. This attribute is read-only. primary-navigation")' returns a value of null even though the class name exists. querySelectorAll('input[type=checkbox]'); Note that radio buttons <input type="radio"> and check boxes <input type="checkbox"> are both input tags with a different `type attribute. setUserAgent(UserAgen document. This post walks through how you can create a safe querySelector for use in TypeScript code and explains how this is an example of a general pattern of using values (which exist at runtime) as a source of truth, rather than types (which don't). textContent = styles document. Here you are getting null so no matches found with this selector. nf-breadcrumbs li'); in the console it returns the correct NodeList. addEventListener method to listen to the event emitted by the html element. 1. 0. highlighted')!. , document. Apr 10, 2025 · The Document method querySelector() returns the first Element within the document that matches the specified CSS selector, or group of CSS selectors. The event handler is not successfully attached to the button, and if you dig in the console you’ll see an error: TypeError: elem is null. This article will discuss the common issue of null properties and provide solutions to help you overcome this you have a few options: Mess with the // @run-at script setting to try to run later (not guaranteed to work consistently. Mar 16, 2018 · Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. ). Aug 13, 2021 · We add the event handler with the document. Here's the corrected JavaScript code: Apr 10, 2025 · The Document method querySelector() returns the first Element within the document that matches the specified CSS selector, or group of CSS selectors. json file: "manifest_version": 2, Jun 3, 2018 · This doesn't work--return document. Modified 2 years, 10 months ago. querySelector('link[rel="service"]'). Jul 5, 2020 · In a debugger I can see that querySelector returns null regardless of the selector I used. Here is my HTML: &lt;!DOCTYPE html& Jul 23, 2024 · Hi, I have the following code (more or less) in a Firefox extension: var styles = ` . classList; Code language: JavaScript (javascript) In this example, we select an element with id save and access its classList property. However, Chrome still returns null. contentDocument. For instance, I tried the following in the live debugger: > container. $$('. querySelector返回null。以下是我的HTML： Sep 1, 2021 · Meanwhile, document. 当使用 document. addEventListener("load"), my document. Não estou conseguindo identificar o porque deste erro estar acontecendo nem como resolvê-lo. Feb 3, 2021 · Alternatively if you know from the context of your program that this query will not return null, you can use a TypeScript non-null assertion (!): document. Aug 29, 2024 · Therefore, when the browser executes document. However, if I use document. style. – Jul 9, 2020 · document. Solution: You can return an ElementHandle, which is a representation of an in-page DOM element, back to the Node. The current page I'm seeing this problem with is www. querySelector() 返回 null 的情况. querySelector('#save'). 5. log still returns null. querySelector return an Element OR Null. querySelector('#your-box')) In this case, you can use the backticks: document. var iframe_jquery = $("<iframe>") . Reproduction: Problem description: The provided documentation doesn't match what is necessary to make this work. Jan 5, 2017 · document. The nodes can be accessed by index numbers. querySelector('#my-paragraph') selects the first element with the ID my-paragraph. querySelector() 方法将返回 null。 Oct 3, 2023 · document. querySelector(), it returns nothing (technically, it returns null), because there is no element to find (yet)! This test page on JSFiddle shows this. build the aforementioned automatic return mechanism). Since it looks like you're trying to query by a class, add the period to denote it is such. querySelector("div. Mar 3, 2024 · const el = document. it returns null. selector'); var selection = document. querySelector("button") null > container. Sep 28, 2020 · Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Jun 30, 2018 · The contentWindow property returns the Window object generated by an iframe element (through the window object, you can access the document object and then any one of the document's elements). createElement("style") styleSheet. getElementById('my-row'); (myRow. Can anyone please help me understand why this Queryselector returns null when trying to access the div element? Feb 29, 2024 · The querySelector method has a return type of Element | null. Jan 6, 2019 · Problem: querySelector returns null on DOM element that is clearly visible: I believe that you cannot get proper value using document. selector') !== null; the second statement contains the actual value of document. querySelector('#b>a'); console. querySelector in JavaScript. Returns null if no matches are found; otherwise, it returns the first matching element. Part of that, for React especially, is the performance benefits that can be had when you let the library figure out the delta that needs to happen between one state and another. js environment because they are separate. It does not work at all for this particular page under test (always returns null). querySelectorAll returns null for any inquiry. (source: MDN) This method is a part of the Document interface. querySelector returns null. querySelector() 方法时，如果没有匹配的元素，则返回 null。这通常出现在以下情况： 选择器没有匹配的元素. Mar 27, 2024 · To overcome the problem of querySelector returning null, you can follow these solutions: Check if the element exists. First, I followed this video, but null is returned when the func Jul 27, 2022 · Document. $$() to obtain an ElementHandle array: let list = await page. addClass("foo") . Dec 3, 2021 · Despite putting the document. var selection = document. VueJS test-utils can't find element inside child component. NEAR { display:block; } ` window. May 25, 2020 · document. log(document. TypeScript is fore-warning you about this possibility. querySelector<E extends Element = Element>(selectors: string): E | null; This is a mismatch for both, to fix this, you will need to cast the return object from querySelector. manifest. 0 Can't get selenium to find element and select it. querySelectorAll([css selector]). Related questions. I will be very grateful for your help. I want to track changes to an element on a page using MutationObserver, but I get null when trying to find the element I need. Viewed 704 times -1 . Dec 20, 2023 · querySelector() and querySelectorAll() are two jQuery functions which helps the HTML elements to be passed as a parameter by using CSS selectors ('id', 'class') can be selected. querySelector("input. com. You can use the console. Jul 27, 2020 · The DOM's document. querySelector is returning null is that the DOM does not contain that element yet. evaluate runs in the emulated page context, not in the standard scope of the Node script. NEAR'); But element is always null… I’ve also tried adding the style section to document. querySelector method in JavaScript. querySelector('container') i get this error: error Jul 31, 2017 · **UPDATED ** with a solution that comes close to working: I'm trying to get my 'skip to content' link to jump to the first focusable element after '#content-start'. However, anytime I try to store the divs with a class of . querySelector() 方法返回 null 的情况. querySelector("#modelTable > tbody"); que sempre retorna null. js environment. To use an ID selector in CSS, you write a hashtag # followed by the ID of the element but there is no need and actually very confusing and wrong to add the # in the value of the attribute. An Element object or null if no element matches the selectors. And so casting it to HTMLInputElement as I wrote in my comment works: let myRow = document. Not sure if this doesn't work with polymer (no reason it shouldn't) or I haven't imported something or what else is wrong. So to select those you Apr 2, 2020 · Unfortunately, querySelector always returns null no matter what selector I pass to it. querySelectorメソッドの戻り値がnullかどうかをチェックすることで、要素が見つからない場合の処理を適切に行うことができます。 document. 2. Aug 26, 2024 · This is why it's important to run through the minimal reproducible example exercise: take your code, and throw away everything that isn't involved in the problem. Apr 20, 2022 · I want to call a function when a button within an iframe is clicked, but I am already having problems accessing the iframe document. querySelector(#${YOU['div']}) Mar 20, 2025 · Document. As a front-end developer with 5 years of experience, you may have encountered a weird situation when working with the document. getElementById('#hello') // will return null 尽管将document. Essentially, if for whatever reason no element in your DOM matches that selector query (. Apr 15, 2016 · The way you're using it, document. e. A common issue when using document. Suggested solution: Fix it somehow, but I'm not sure why it's not working. getElementById() returns NULL in ReactThe document. # [Solved]: document. Aug 14, 2013 · I'm using the waitForSelector() and captureSelector() methods in CasperJS to wait for and select an element using a CSS selector, then save a screenshot of it. querySelector returns null until element is inspected using DevTools, however there are some significant differences that are quite confusing and suggest that the problem may be different. querySelector always returns null. I can't figure out why it behaves like this. log(x); var y = Mar 29, 2021 · OK, so now you basically just need to add '#' to your querySelector, so it'll be looking for an element with an id 'your-box' (document. hence iframe. Apr 7, 2022 · To put it as simply as we can, querySelector is a method for finding elements on any website. querySelector<HTMLElement>('. let classList = document. querySelectorとquerySelectorAllの違い Nov 21, 2019 · document. I. 0 Selenium WebDriver Unable to Find Element by Id, Using Nov 11, 2020 · The querySelector returns null on the marked line while when using select by a class (like on the next line) it works fine. some-class), you'll get null back. You can't return DOM nodes back to Puppeteer--it must be serializable data. getElementsByClassName() to check if an element with a given class exists. querySelectorAll, which returns an iterable NodeList (or null) that does not require testing on the returned data before performing work on it. I've tried using the selectors *, form, and form#mini_search_form for this page and all return null. If the selector matches an ID and this ID is erroneously used several times in the document, it returns the first matching element. Gostaria que alguém pudesse me explicar o porque disto estar acontecendo, e me dar uma dica de como solucionar este problema. QuerySelector returns null from a name given in javascript array. Wait for some meaningful event. The difference is: var canvas=document. querySelector() with TypeScript is handling potentially null values, as the method returns null if no elements match the selector. card in the const questionCard, I get null. querySelectorAll #. May 17, 2024 · このように、document. log still returns null so I'm a bit puzzled. forEach(function (element) { [business logic using element] }); Jan 15, 2022 · I did try it with a regular class and the Queryselector found the element, but in this project, I need to use modules. If the page doesn’t have any element with the id save, the document. contentWindow. Dec 8, 2020 · So I'm building a multi form with tabs, however when I try to log the const: const breadcrumbs = document. Oct 17, 2013 · A current issue I'm having is that for some webpages I try to scrape, for some reason, getElementsInfo, and evaluate document. Ask Question Asked 4 years, 9 months ago. A string containing one or more CSS selectors to match. selector') is null or not. nf-breadcrumbs li'); It returns an empty NodeList, however when I use document. log (el); // 👉️ null // ⛔️ Cannot read properties of null (reading 'querySelectorAll') el. The matching is done using depth-first pre-order traversal of the document's nodes starting with the first element in the document's markup and iterating Both are array-like collections (lists) of nodes (elements) extracted from a document. Then if you try to read the . Here is the HTML for the example. Nov 9, 2023 · With React, like a lot of frameworks, the idea is to get people away from thinking about the DOM and thinking more about their data/state. After clicking button, alert is not showing up. Mar 29, 2017 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand myVar = document. body and directly to the Apr 10, 2014 · The first statement contains a bool value depends on document. If no element with the provided selector exists in the DOM, the method returns a null value. appendChild(styleSheet) const element = document. my-element')); Dec 24, 2016 · I use the following code to dynamically create an iframe. querySelector method is ubiquitious in JavaScript but somewhat tricky to type in a safe way. querySelector('#overlay-root') as Element, It is a "react" library, react-chart-js-2, which seems to be chartjs with some slight adaptations to react. readyState); console. querySelector() Method: The querySelector() method returns the first element within the document which matches a specified Oct 12, 2017 · I use the querySelector in JS to select html markup that I filled in with a JS script. I tried chaining them together but still I eventuall May 28, 2022 · Ran into a problem that querySelector() returns null for an element that exists on the page. querySelector('#save') returns null. querySelector('#test')); The reason the readyState is already complete is the iframe has a content document when it is created, well before the new content -- with the test element -- has been loaded. selector'); Oct 31, 2020 · But if I choose container instead of the main element (this is the first child element of the main element) in the 3rd code line const mainElement = document. email"); 它将返回具有’class’属性为’email’的第一个输入元素。 Oct 1, 2021 · JSでDOMを取得する際に使用するquerySlectorやgetElementByIdなど。とても便利だけど、読み込み順番を間違えると「null」つまり「無いよ」と言われてしまいます。今回はそんなDOM取得の際の読み込み順番についての解決策についてのお話です。 Oct 5, 2023 · I'd like something as elegant as document. querySelector<"body">(selectors: "body"): HTMLBodyElement | null (+2 overloads) Returns the first element that is a descendant of node that matches selectors. appendTo(container); // container is a jQuery object Jun 25, 2019 · TypeScript is warning you that el. Conditionally rendering message on HTML page from Typescript in runtime Aug 3, 2014 · For some reason document. May be Apr 7, 2023 · If the iframe and the iframe's parent document are Same Origin, returns a Document (that is, the active document in the inline frame's nested browsing context), else returns null. Return value. Then we make sure that the input element is already loaded by putting the document. It seems my 'const primary_nav = document. Jul 22, 2020 · componentDidMount() { var element = document. querySelector in a window. Before using the querySelector method, ensure that the element exists in the HTML document. log() method to check the value of the querySelector method. textContent of null, that'll throw an exception. Asking for help, clarification, or responding to other answers. querySelectorAll("tabbable") is looking for an element of the tag <tabbable>. backgroundColor = 'white'; Jun 19, 2024 · Solving Null Property Issues with document. Jul 12, 2022 · document. myClass') as HTMLInputElement). getElementById('. value = " a vaule"; Aug 30, 2021 · let selects = document. getElementById('hello') This is our good old way to access an id (not a class). querySelector returns only the first element that matches the given selector, while querySelectorAll returns a NodeList of all the elements matching the selector. querySelectorAll returns a static Apr 7, 2024 · You can also use the document. g. querySelectorAll(). with querySelector in a recursive setTimeout or a setInterval) the DOM using querySelector until it does appear (i. getElementById ('container'); console. Aug 9, 2017 · querySelector returns null when searched for the id "#b>a", but getElementById returns the correct element. Console. I almost never use for loops anymore (favoring pure higher order functions and utilizing array methods like map instead), so I forget about some of the idiosyncrasies of a raw loop. The TypeScript compiler, especially with strict null checks enabled, will enforce proper checking of null values. What's going on? var x = document. price'). If we have to access any element-specific properties on the variable, we have to use a type assertion to type it correctly Jun 15, 2023 · I'm following Kevin Powell's tutorial on creating a responsive navbar when I encountered this problem. getElementById("canvas");. Jun 7, 2021 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Feb 20, 2022 · ts中document. querySelector works but querySelectorAll doesn't-1. 当调用 document. Exceptions Nov 18, 2017 · Oh yes. querySelector is returning null for both class and id selectors. querySelector on the "sign-in-box" returns null. select')`の結果がnullとなりますが、何か誤りがありま Jan 1, 2022 · The CSS id selector uses the ID attribute of an HTML element to select one unique element on a page. If no matches are found, null is returned. Aug 7, 2019 · `[]. querySelectorAll('input[type=radio]'); let checkbox = document. Besides the querySelector(), you can use the querySelectorAll() method to select all elements that match a CSS selector or a group of CSS selectors: Dec 5, 2014 · Per the answer by @AmitJoki, the line var elem = document. I looked up stackover flow for some answers, I tried: waitForSelector() &amp; page. Example of contentDocument Jan 12, 2022 · My problem appears to be quite similar to this problem: Document. Apr 9, 2021 · On this page and in the videos I watched, everything worked and returned &lt;h1&gt; Hello &lt;/h1&gt;. document. querySelector tutorial shows how to use querySelector to select HTML elements in JavaScript. That makes sense. var el = document. The querySelector() method is available on the document object or any Element object. querySelector('. May 8, 2016 · This solution does the following: Uses the ES6 spread operator to convert the NodeList of all divs to an array. If no element matches the CSS selectors, the querySelector() returns null. querySelector does not return this one particular element. NodeList is always empty when running querySelectorAll() 2. querySelector, it works as expected. querySelectorAll ('div. console. Provide details and share your research! But avoid …. querySelector() instead of document. querySelector() 方法查询元素时，有一些情况会返回 null。以下是一些可能导致返回 null 的情况： 选择器没有匹配的元素： 如果使用的选择器在文档中没有匹配的元素，那么 document. You can also use the document. querySelector HTML document. querySelector(parameter); Parameters. The index starts at 0. The problem is that you are using document. e. The script setup runs when the component is created, so the component's DOM has not been created yet. log('init', iframe. querySelector("div") null I'm clearly doing something spectacularly wrong. querySelectorAll('select'); let radioInputs = document. You can use this Window object to access the iframe's document and its internal DOM. querySelector报错如何处理呢？感谢！ ParentNode. queryselector returns null value. getElementById() method returns null in React when we call the method before the element with the provided ID has been rendered to the DOM or if an element with the ID doesn't exist. E. Oct 29, 2020 · document. Obviously attaching the event to null instance fails and results in Sep 26, 2018 · You are trying to get element pausebuttons with query selector but that is null. href, should be var elem = document. user-panel. I am currently building a May 28, 2019 · However, I realized now that I skipped important information - the problem is not that document. Apr 13, 2018 · vue-test-utils returns null for document. querySelector('link[rel="service"]'),. Oct 30, 2019 · querySelector() の場合には戻り値がnullなのでこれでいいのですが、querySelectorAll() を使った時にほんの少しハマったので共有しておきます。 Chrome Developer Tool のコンソールで動作を確認してみます。 querySelector() のケース May 30, 2021 · Preventing Errors with document. textContent;. . solesociety. 当指定的选择器没有匹配的元素时，document. However, I'm finding that because the css background has been set to transparent, the screenshot turns out pretty ugly, so I'd like to set the background to white. main input[name='login']"); Notes. title'); Dec 12, 2020 · The callback passed to page. The Document method querySelector returns the first Element within the document that matches the specified selector, or group of selectors. addEventListener("load")中，但“登录框”上的document. But i have some specific requirements like having a fixed text in the middle of a donut chart so i have to position the chart absolutely, since it's rendered as a canvas, so i have to set the size of the wrapper div manually. I have also tried to use DOMContentLoaded in order to execute my code after the DOM has been loaded since I suspect this is a DOM issue. querySelector() returns null in my code but works fine if I type it in the chrome inspector. Apr 4, 2022 · The reason document. Provides output if the div contains the query string, not just if it exactly equals the query string (which happens for some of the other answers). ztujgx amk otjjid aabj cmcja tesji insvlv wxt inb kavvyusi vnf riz gjyk hqj lvrns