Exploring useImperativeHandle in React: Customizing Refs with Dependencies

In React, refs are often used to directly access or manipulate DOM elements. However, there are scenarios where you might want to expose a custom interface to parent components, encapsulating complex functionality. This is where the useImperativeHandle hook comes into play. In this blog post, we'll dive into useImperativeHandle, exploring its syntax, use cases, and how to use it with dependencies.

What is useImperativeHandle?

useImperativeHandle is a React Hook that allows you to customize the instance value that is exposed when using ref objects. It enables parent components to interact with child components in a controlled manner, avoiding direct manipulation of child component internals.

useImperativeHandle(ref, createHandle, [deps])

• ref: The ref object passed from the parent component.
• createHandle: A function that returns the custom value to be assigned to the ref.
• [deps]: An optional array of dependencies that, when changed, will re-create the handle.

Basic Example

Let’s start with a basic example to understand how useImperativeHandle works.

Let’s start with a basic example to understand how useImperativeHandle works.

import React, { useRef, useImperativeHandle, forwardRef } from 'react';
const CustomInput = forwardRef((props, ref) => {
  const inputRef = useRef();
  useImperativeHandle(ref, () => ({
    focus: () => {
      inputRef.current.focus();
    },
    value: () => {
      return inputRef.current.value;
    },
  }));
  return <input ref={inputRef} {...props} />;
});
const ParentComponent = () => {
  const inputRef = useRef();
  const handleFocus = () => {
    inputRef.current.focus();
  };
  const handleGetValue = () => {
    alert(inputRef.current.value());
  };
  return (
    <div>
      <CustomInput ref={inputRef} />
      <button onClick={handleFocus}>Focus Input</button>
      <button onClick={handleGetValue}>Get Input Value</button>
    </div>
  );
};
export default ParentComponent;

In this example, CustomInput uses useImperativeHandle to expose focus and value methods to the parent component. This allows the parent component to focus the input and get its value through the ref.

Using useImperativeHandle with Dependencies

Now, let’s extend the example to include dependencies. We’ll create a custom input component that allows the parent component to change the color of the input text dynamically.

import React, { useRef, useImperativeHandle, forwardRef, useState } from 'react';const CustomInput = forwardRef((props, ref) => {
  const inputRef = useRef();
  const [color, setColor] = useState('black');useImperativeHandle(ref, () => ({
    focus: () => {
      inputRef.current.focus();
    },
    setValue: (value) => {
      inputRef.current.value = value;
    },
    changeColor: (newColor) => {
      setColor(newColor);
    },
  }), [color]);
 return <input ref={inputRef} style={{ color }} {...props} />;
});
const ParentComponent = () => {
  const inputRef = useRef(); const handleFocus = () => {
    inputRef.current.focus();
  };const handleSetValue = () => {
    inputRef.current.setValue('Hello, World!');
  }; const handleChangeColor = () => {
    inputRef.current.changeColor('blue');
  };
return (
    <div>
      <CustomInput ref={inputRef} />
      <button onClick={handleFocus}>Focus Input</button>
      <button onClick={handleSetValue}>Set Input Value</button>
      <button onClick={handleChangeColor}>Change Input Color</button>
    </div>
  );
};
export default ParentComponent;

Explanation

1.CustomInput Component:

• Uses forwardRef to forward the ref to the CustomInput component.
• Inside CustomInput, useRef is used to create a reference to the actual input element.
• useState is used to manage the color state of the input element.
• useImperativeHandle is used to customize the ref, exposing focus, setValue, and changeColor methods. The color state is added to the dependency array, so the handle is re-created whenever color changes.

Explanation

CustomInput Component:

• Uses forwardRef to forward the ref to the CustomInput component.
• Inside CustomInput, useRef is used to create a reference to the actual input element.
• useState is used to manage the color state of the input element.
• useImperativeHandle is used to customize the ref, exposing focus, setValue, and changeColor methods. The color state is added to the dependency array, so the handle is re-created whenever color changes.

ParentComponent:

• Uses useRef to create a ref object that is passed to CustomInput.
• Provides buttons to call the methods defined in useImperativeHandle (focus, setValue, and changeColor), allowing the parent component to interact with the CustomInput component.

Why Use useImperativeHandle?

• Encapsulation: It helps encapsulate complex functionality within a component, providing a clean interface for parent components.
• Controlled Interactions: It allows parent components to interact with child components in a controlled manner, avoiding direct manipulation of child component internals.
• Customization: It enables you to expose a custom interface to parent components, tailored to the specific needs of your application.

Conclusion

useImperativeHandle is a powerful hook in React that allows you to customize refs and expose a tailored interface to parent components. By using dependencies, you can ensure that the handle is updated whenever necessary, providing a dynamic and flexible way to interact with child components. Whether you are building complex components or encapsulating specific functionality, useImperativeHandle can be a valuable tool in your React toolkit.