useRef Hook

Introduction

The useRef Hook allows you to create a mutable reference that persists throughout the component's lifecycle. It is useful for accessing and manipulating DOM elements directly, maintaining any mutable value that does not cause a re-render when it changes, and storing previous values between renders.

Basic Syntax

useRef is used to create a reference and can be assigned to DOM elements.

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Example Description

In this example:

• inputEl is a reference created with useRef.
• inputEl is assigned to the input element, so inputEl.current points to the DOM node.
• The function onButtonClick focuses the input by calling inputEl.current.focus().

Other useRef Applications

useRef is not only for manipulating the DOM; it can also hold any mutable value between renders that does not cause a re-render when it changes.

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Advanced Example Description

In this example:

• countRef is used to store the current value of count so that the setInterval interval always has the latest value without needing to be stopped and restarted.

Common useRef Uses

• Direct access to DOM elements: Focusing inputs, stopping animations, manipulating canvas, etc.
• Storing previous instance values: Keeping a reference to previous values without causing a re-render.
• Holding any mutable value: Ideal for storing data that needs to persist through renders but should not cause a re-render.

Difference between useRef and useState

While useState causes the component to re-render when its value changes, useRef does not. This makes useRef more suitable for values that change frequently and do not need to trigger re-renders, such as interval IDs or any other mutable reference.

Warnings

Although useRef is powerful, it should be used with caution: it can lead to difficult-to-debug behavior if combined with uncontrolled DOM mutations or complex application logic.

[Placeholder for an image about the use of useRef: Diagram showing how useRef interacts with the DOM, including the creation of references and their use in direct DOM manipulations.]