Document queryselector returns null querySelectorAll(). May 8, 2016 · This solution does the following: Uses the ES6 spread operator to convert the NodeList of all divs to an array. Aug 29, 2024 · Therefore, when the browser executes document. querySelector("canvas"); is getting the element from tag name canvas. 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. 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. 1. Here you are getting null so no matches found with this selector. Aug 25, 2024 · This is my first time trying to make a Chrome extension. 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. solesociety. it returns null. Apr 15, 2016 · The way you're using it, document. 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. Apr 13, 2018 · vue-test-utils returns null for document. Aug 9, 2017 · querySelector returns null when searched for the id "#b>a", but getElementById returns the correct element. querySelector on the "sign-in-box" returns null. myClass') as HTMLInputElement). Gostaria que alguém pudesse me explicar o porque disto estar acontecendo, e me dar uma dica de como solucionar este problema. querySelector in JavaScript. box'); Instead, you should move the JS script tag to the bottom of the body, after the elements it tries to access. querySelectorAll, which returns an iterable NodeList (or null) that does not require testing on the returned data before performing work on it. However, if I use document. querySelector works but querySelectorAll doesn't-1. Modified 2 years, 10 months ago. hello') // will return null Also, note that you don't need to pass # in this function argument. That makes sense. 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. 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. 0. 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. forEach. querySelector method in JavaScript. As a front-end developer with 5 years of experience, you may have encountered a weird situation when working with the document. querySelector() 方法将返回 null。 Oct 3, 2023 · 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. The nodes can be accessed by index numbers. Reproduction: Problem description: The provided documentation doesn't match what is necessary to make this work. 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. Googled and found out about "run_at": "document_end" and added it in my manifest file but my console. 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. However, anytime I try to store the divs with a class of . Since it looks like you're trying to query by a class, add the period to denote it is such. If you're not using strictNullChecks then Element, and it doesn't have the value member. getElementById("canvas");. setUserAgent(UserAgen document. The difference is: var canvas=document. querySelector放在window. I'm already despera Aug 2, 2021 · The querySelector method returns Element | null. getElementById() returns NULL in ReactThe document. manifest. 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. Related questions. # [Solved]: document. You can use this Window object to access the iframe's document and its internal DOM. May 2, 2023 · console. user-panel. 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. getElementById('hello') This is our good old way to access an id (not a class). Dec 3, 2021 · Despite putting the document. I. querySelectorAll('. querySelector() returns null. I will be very grateful for your help. It seems my 'const primary_nav = document. Conditionally rendering message on HTML page from Typescript in runtime Aug 3, 2014 · For some reason document. # Check if a DOM element exists using getElementsByClassName. 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'. querySelector("#modelTable > tbody"); que sempre retorna null. querySelector() instead of document. querySelector("div") null I'm clearly doing something spectacularly wrong. querySelector is returning null for both class and id selectors. querySelector() 方法返回 null 的情况. 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. Jul 5, 2020 · In a debugger I can see that querySelector returns null regardless of the selector I used. contentWindow. 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. Here is the HTML for the example. evaluate runs in the emulated page context, not in the standard scope of the Node script. 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. Apr 7, 2022 · To put it as simply as we can, querySelector is a method for finding elements on any website. querySelectorAll('select'); let radioInputs = document. Mar 3, 2024 · const el = document. Use page. (source: MDN) This method is a part of the Document interface. Then we make sure that the input element is already loaded by putting the document. A Sep 23, 2017 · In other words, you cannot return an element from the page DOM environment back to the Node. I can't figure out why it behaves like this. body and directly to the Apr 10, 2014 · The first statement contains a bool value depends on document. console. 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). 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. com. e. Mar 27, 2024 · To overcome the problem of querySelector returning null, you can follow these solutions: Check if the element exists. 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. So to select those you Apr 2, 2020 · Unfortunately, querySelector always returns null no matter what selector I pass to it. querySelector<"body">(selectors: "body"): HTMLBodyElement | null (+2 overloads) Returns the first element that is a descendant of node that matches selectors. addEventListener("load")中，但“登录框”上的document. log still returns null. Aug 13, 2021 · We add the event handler with the document. querySelectorAll returns a static Apr 7, 2024 · You can also use the document. querySelector in a window. 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. g. If the selector matches an ID and this ID is erroneously used several times in the document, it returns the first matching element. querySelectorAll returns null for any inquiry. head. textContent;. appendTo(container); // container is a jQuery object Jun 25, 2019 · TypeScript is warning you that el. title'); Dec 12, 2020 · The callback passed to page. href). Here is my HTML: <!DOCTYPE html& Jul 23, 2024 · Hi, I have the following code (more or less) in a Firefox extension: var styles = ` . Asking for help, clarification, or responding to other answers. If no element with the provided selector exists in the DOM, the method returns a null value. 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. An Element object or null if no element matches the selectors. Before using the querySelector method, ensure that the element exists in the HTML document. js environment. highlighted')!. , document. 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. querySelector("button") null > container. price'); should be return document. log still returns null so I'm a bit puzzled. querySelector报错如何处理呢？感谢！ ParentNode. querySelectorとquerySelectorAllの違い Nov 21, 2019 · 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. 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. href, should be var elem = document. var el = document. 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). querySelectorAll([css selector]). querySelectorAll("tabbable") is looking for an element of the tag <tabbable>. querySelector does not return this one particular element. primary-navigation")' returns a value of null even though the class name exists. It does not work at all for this particular page under test (always returns null). The Document method querySelector returns the first Element within the document that matches the specified selector, or group of selectors. readyState); console. Wait for some meaningful event. wrap your code in a addEventListener('load', => { /* your code */ });, but if the site is constructing the page dynamically after load, it won't help. querySelector method in React. json file: "manifest_version": 2, Jun 3, 2018 · This doesn't work--return document. 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. selector') !== null; the second statement contains the actual value of document. querySelector() returns null in my code but works fine if I type it in the chrome inspector. What's going on? var x = document. Example of contentDocument Jan 12, 2022 · My problem appears to be quite similar to this problem: Document. textContent of null, that'll throw an exception. Mar 16, 2018 · Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Solution: You can return an ElementHandle, which is a representation of an in-page DOM element, back to the Node. You can't return DOM nodes back to Puppeteer--it must be serializable data. I've tried using the selectors *, form, and form#mini_search_form for this page and all return null. 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. NEAR { display:block; } ` window. value = " a vaule"; Aug 30, 2021 · let selects = document. NodeList is always empty when running querySelectorAll() 2. 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. 当使用 document. build the aforementioned automatic return mechanism). querySelector('link[rel="service"]'),. contentDocument. let classList = 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. . querySelector("input. querySelector('SVG > a:nth-child(2) > text'). May 25, 2020 · document. May 17, 2024 · このように、document. 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. I am currently building a May 28, 2019 · However, I realized now that I skipped important information - the problem is not that document. Jan 6, 2019 · Problem: querySelector returns null on DOM element that is clearly visible: I believe that you cannot get proper value using document. querySelector method is ubiquitious in JavaScript but somewhat tricky to type in a safe way. 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. If the page doesn’t have any element with the id save, the document. Then if you try to read the . querySelectorAll('input[type=radio]'); let checkbox = document. Aug 19, 2019 · tableBody = document. querySelector('[data-testid="AddToCartButton"]') null > container. 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. querySelector(". main input[name='login']"); Notes. var iframe_jquery = $("<iframe>") . nf-breadcrumbs li'); in the console it returns the correct NodeList. Jul 12, 2022 · document. Both have a length property that returns the number of elements in the list (collection). call`の挙動について学習中ですが、 以下のコードで `document. some-class), you'll get null back. querySelector returns null. card in the const questionCard, I get null. If no matches are found, null is returned. And so casting it to HTMLInputElement as I wrote in my comment works: let myRow = document. 当指定的选择器没有匹配的元素时，document. querySelectorAll #. querySelector返回null。以下是我的HTML： Sep 1, 2021 · Meanwhile, document. 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. The problem is that you are using document. querySelector<HTMLElement>('. The Document method querySelector() returns the first Element within the document that matches the specified selector, or group of selectors. Please note that the querySelector() method returns a single matching element, whereas the querySelectorAll() method returns a list of all matching elements. my-element')); Dec 24, 2016 · I use the following code to dynamically create an iframe. Essentially, if for whatever reason no element in your DOM matches that selector query (. backgroundColor = 'white'; Jun 19, 2024 · Solving Null Property Issues with document. nf-breadcrumbs li'); It returns an empty NodeList, however when I use document. getElementsByClassName() to check if an element with a given class exists. 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. querySelector('. getElementById('my-row'); (myRow. If no element matches the CSS selectors, the querySelector() returns null. querySelector() 返回 null 的情况. querySelector返回null但元素存在. Viewed 704 times -1 . Suggested solution: Fix it somehow, but I'm not sure why it's not working. querySelector returns only the first element that matches the given selector, while querySelectorAll returns a NodeList of all the elements matching the selector. querySelector return an Element OR Null. js environment because they are separate. 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. some-class') may return null. querySelector('link[rel="service"]'). Ask Question Asked 4 years, 9 months ago. 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. querySelectorAll ('div. log() method to check the value of the querySelector method. 5. $$() to obtain an ElementHandle array: let list = await page. 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. Apr 4, 2022 · The reason document. A common issue when using 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. An HTMLCollection is a collection of document elements. getElementById('. querySelector tutorial shows how to use querySelector to select HTML elements in JavaScript. log('init', iframe. querySelector('#b>a'); console. Não estou conseguindo identificar o porque deste erro estar acontecendo nem como resolvê-lo. 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 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". 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. createElement("style") styleSheet. The issue is that you are attempting to access a property of a null value (null. appendChild(styleSheet) const element = document. This attribute is read-only. querySelector('#my-paragraph') selects the first element with the ID my-paragraph. getElementById ('container'); console. In Firefox this returns a NULL. Mar 16, 2025 · Returns a single element object or null if no match is found. 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. log(document. TypeScript is fore-warning you about this possibility. Aug 7, 2019 · `[]. VueJS test-utils can't find element inside child component. E. 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. Returns null if no matches are found; otherwise, it returns the first matching element. 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. querySelector call inside the DOMContentLoaded event handler. styleSheet = document. You can use the console. querySelector("div. 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. querySelector('#your-box')) In this case, you can use the backticks: document. hence iframe. A string containing one or more CSS selectors to match. I looked up stackover flow for some answers, I tried: waitForSelector() & page. var selection = document. querySelector always returns null. selector'); var selection = document. 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. 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. First, I followed this video, but null is returned when the func Jul 27, 2022 · Document. 当调用 document. e. The current page I'm seeing this problem with is www. addEventListener("load"), my document. Jan 5, 2017 · document. The querySelector() method is available on the document object or any Element object. – Jul 9, 2020 · document. 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('#save') returns null. You can also use the document. The index starts at 0. Oct 29, 2020 · document. Console. price'). The TypeScript compiler, especially with strict null checks enabled, will enforce proper checking of null values. 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. Provide details and share your research! But avoid …. querySelector() with TypeScript is handling potentially null values, as the method returns null if no elements match the selector. QuerySelector returns null from a name given in javascript array. 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. querySelector, it works as expected. queryselector returns null value. addClass("foo") . querySelector("canvas"); instead of var canvas=document. Feb 14, 2024 · Handling Null Values. classList; Code language: JavaScript (javascript) In this example, we select an element with id save and access its classList property. 0 Can't get selenium to find element and select it. $$('. After clicking button, alert is not showing up. querySelector is returning null is that the DOM does not contain that element yet. 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. Exceptions Nov 18, 2017 · Oh yes. 2. 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. 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. Dec 8, 2020 · So I'm building a multi form with tabs, however when I try to log the const: const breadcrumbs = document. 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. document. ). You can't access class by doing something like. style. Jul 27, 2020 · The DOM's document. Apr 9, 2021 · On this page and in the videos I watched, everything worked and returned <h1> Hello </h1>. For instance, I tried the following in the live debugger: > container. 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). 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. selector') is null or not. The script setup runs when the component is created, so the component's DOM has not been created yet. Return value. document. 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. 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('#save'). with querySelector in a recursive setTimeout or a setInterval) the DOM using querySelector until it does appear (i. 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. querySelector('main'), and line becomes const mainElement = document. 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. querySelector(#${YOU['div']}) Mar 20, 2025 · Document. querySelector(), it returns nothing (technically, it returns null), because there is no element to find (yet)! This test page on JSFiddle shows this. NEAR'); But element is always null… I’ve also tried adding the style section to document. getElementById('#hello') // will return null 尽管将document. querySelector HTML document. — You are receiving this because you are subscribed to this thread. addEventListener method to listen to the event emitted by the html element. However, Chrome still returns null. returns an undefined Mar 5, 2024 · If neither element is found, the querySelector() method returns null. 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. textContent = styles document. querySelector(parameter); Parameters. Jul 22, 2020 · componentDidMount() { var element = document. mboxmbrnepyyqbnphqiwirofcxqphhmitfqilgwccdpfqsxmvphqdokbjqkeiewyomqxhwvy