That's why only the first highlights, no matter which one you focus on. With our knowledge so far, the only way to update the UI is to create a new element, and pass it to ReactDOM.render(). The getElementById() method returns the element that has the ID attribute with the specified value. By David Walsh on May 14, 2018 3; JSX is an amazing pseudo-language for React, and if I'm honest, it's what brought me to love React so much.

Do this by passing the element a unique ref : render: function() { return ; },

If you need to get access to an element which doesn't have an ID, you can use querySelector() to find the element using any selector. Newcomers to React might not find refs to be intuitive, but they are important. Returns null if no elements with the specified ID exists. Using React without JSX is cumbersome and frustrating, while using JSX is such an easier way to express your code. This method is one of the most common methods in the HTML DOM, and is used almost every time you want to manipulate, or get info from, an element on your document. Updating the Rendered Element . The ID is case-sensitive string which is unique within the document; only one element may have any given ID. Once you create an element, you can’t change its children or attributes.

Or you need to use a single ID more than two times. This will return the same ID twice in a row, a simplification available for the most common scenario. When any of the components asks for the element with ID myInput, the browser hands back the first one. How to Get a React Component’s Element. Syntax var element = document.getElementById(id); Parameters id The ID of the element to locate. Here's why you should never use an ID when you can use a ref. An element is like a single frame in a movie: it represents the UI at a certain point in time. The Solution: refs. Adding a Ref to a Class Component . In many cases though, you either need the IDs in an interspersed order, making it impossible to call getNextHtmlFor twice in a row to get the ID. React will assign the current property with the DOM element when the component mounts, and assign it back to null when it unmounts.ref updates happen before componentDidMount or componentDidUpdate lifecycle methods.. React elements are immutable. To access an element’s DOM node using this.refs, you’ll first need to let React know that you actually care about that particular node.