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JS get the height and width corresponding to the box model (window.getcomputedstyle, dom.getboundingclientrect)

2022-06-25 14:27:00 【Fat goose 68】

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Article reference

obtain dom General method of node height and width

dom.style.width/height ( Only applicable to get the width and height of inline elements )
dom.currentStyle.width/height ( Get the width and height after rendering , But only IE Support )
window.getComputedStyle(dom).width/height ( And 2 Principle similarity , But compatibility , Commonality will be better )
dom.getBoundingClientRect().widht/height ( Calculate the absolute position of the element , Get four elements left,top,width,height)

Case description

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style> #xiding-header{
      border: 1px solid red; } .box {
      height: 500px; } .fixed-top {
      position: fixed; top: 0; left: 0; right: 0; } </style>
<body>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div id="xiding-header" >
    dasfdsfadsafdsaf
  </div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
</body>
<script> let targetDom = document.querySelector('#xiding-header') setTimeout(function () {
      //  Because the target element has no inline style , So it's empty  console.log(targetDom.style.height) //  If it is to use  chrome  open , You can get the height of the target control  console.log(getComputedStyle(targetDom).height) }, 1000) document.addEventListener("scroll", function () {
      console.log(document.documentElement.scrollTop) let boundingObj = targetDom.getBoundingClientRect() console.log(' Height of control  ： ' + (boundingObj.bottom - boundingObj.top)) console.log(' Width of the control  ： ' + (boundingObj.right - boundingObj.left)) if (boundingObj.top <= 0) {
      // targetDom.classList  This method is compatible , Apply to chrome  browser  targetDom.classList.add('fixed-top') //  Conventional DOM  Add attribute , standard API // targetDom.setAttribute("class", 'fixed-top' ); } }) </script>
</html>

Running results ：

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getBoundingClientRect() obtain DOM The height and width of the approach ？

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let targetDom = document.querySelector('#xiding-header')
let boundingObj = targetDom.getBoundingClientRect()
console.log(' Height of control  ： ' + (boundingObj.bottom - boundingObj.top))
console.log(' Width of the control  ： ' + (boundingObj.right - boundingObj.left))