JIYIK CN >

Get the height and width of the parent in React:

1. Sets the attribute on the element ref.
2. In useEffectthe hook, update the state variables for height and width.
3. Use the offsetHeightand offsetWidthproperties to get the height and width of an element.

import {useEffect, useRef, useState} from 'react';

export default function App() {
  const ref = useRef(null);

  const [height, setHeight] = useState(0);
  const [width, setWidth] = useState(0);

  useEffect(() => {
    setHeight(ref.current.offsetHeight);
    setWidth(ref.current.offsetWidth);

    // 👇️ 如果您需要访问设置 ref 的元素的父级
    console.log(ref.current.parentElement);
    console.log(ref.current.parentElement.offsetHeight);
    console.log(ref.current.parentElement.offsetWidth);
  }, []);

  return (
    <div ref={ref}>
      <h2>Width: {width}</h2>

      <h2>Height: {height}</h2>
    </div>
  );
}

useRef()The hook can be passed an initial value as an argument. The hook returns a mutable ref object whose .currentattributes are initialized to the passed argument.

注意, we must access the current property of the ref object to access the div element on which we set the ref attribute.

When we pass a ref prop to an element, for example <div ref={myRef} />, React .currentsets the property of the ref object to the corresponding DOM node.

We pass an empty dependencies array to useEffectthe hook, so it will only run when the component is mounted.

useEffect(() => {
  setHeight(ref.current.offsetHeight);
  setWidth(ref.current.offsetWidth);

  // 👇️ 如果您需要访问设置 ref 的元素的父级
  console.log(ref.current.parentElement);
  console.log(ref.current.parentElement.offsetHeight);
  console.log(ref.current.parentElement.offsetWidth);
}, []);

We use useEffectthe hook because we need to wait for the ref to be set on an element and wait for the element to be rendered before accessing its offsetHeightand offsetWidthattributes.

offsetHeightProperty returns the height of an element in pixels, including vertical padding and border.

offsetWidthProperty returns the width of the element in pixels, including any borders, padding, and vertical scroll bar (if any).

If we need to access the width and height of the parent element of the element on which ref is set, use parentElementthe properties.

console.log(ref.current.parentElement);
console.log(ref.current.parentElement.offsetHeight);
console.log(ref.current.parentElement.offsetWidth);

parentElementThe parent property returns the parent element of a DOM node, or null if the node has no parent or its parent is not a DOM element .

We can also use the clientHeightand clientWidthattributes.

useEffect(() => {
  setHeight(ref.current.clientHeight);
  setWidth(ref.current.clientWidth);

  // 👇️ 如果您需要访问设置 ref 的元素的父级
  console.log(ref.current.parentElement);
  console.log(ref.current.parentElement.clientHeight);
  console.log(ref.current.parentElement.clientWidth);
}, []);

clientWidthProperty that returns the width of an element in pixels, including padding but excluding borders, margins, and the vertical scroll bar (if any).

clientHeightThe property returns the intrinsic height of an element in pixels. It includes padding but excludes borders, margins, and the horizontal scroll bar (if present).