NonDocumentTypeChildNode.previousElementSibling - Web APIs 编辑

The NonDocumentTypeChildNode.previousElementSibling read-only property returns the Element immediately prior to the specified one in its parent's children list, or null if the specified element is the first one in the list.

Syntax

prevNode = elementNodeReference.previousElementSibling;

Example

<div id="div-01">Here is div-01</div>
<div id="div-02">Here is div-02</div>
<li>This is a list item</li>
<li>This is another list item</li>
<div id="div-03">Here is div-03</div>

<script>
  let el = document.getElementById('div-03').previousElementSibling;
  document.write('<p>Siblings of div-03</p><ol>');
  while (el) {
    document.write('<li>' + el.nodeName + '</li>');
    el = el.previousElementSibling;
  }
  document.write('</ol>');
</script>

This example outputs the following into the page when it loads:

Siblings of div-03

   1. LI
   2. LI
   3. DIV
   4. DIV

Polyfills

Polyfill for Internet Explorer 8

This property is unsupported prior to IE9, so the following snippet can be used to add support to IE8:

// Source: https://github.com/Alhadis/Snippets/blob/master/js/polyfills/IE8-child-elements.js
if(!("previousElementSibling" in document.documentElement)){
  Object.defineProperty(Element.prototype, "previousElementSibling", {
    get: function(){
      var e = this.previousSibling;
      while(e && 1 !== e.nodeType)
        e = e.previousSibling;
      return e;
    }
  });
}

Polyfill for Internet Explorer 9+ and Safari

// Source: https://github.com/jserz/js_piece/blob/master/DOM/NonDocumentTypeChildNode/previousElementSibling/previousElementSibling.md
(function (arr) {
  arr.forEach(function (item) {
    if (item.hasOwnProperty('previousElementSibling')) {
      return;
    }
    Object.defineProperty(item, 'previousElementSibling', {
      configurable: true,
      enumerable: true,
      get: function () {
        let el = this;
        while (el = el.previousSibling) {
          if (el.nodeType === 1) {
            return el;
          }
        }
        return null;
      },
      set: undefined
    });
  });
})([Element.prototype, CharacterData.prototype]);

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• The NonDocumentTypeChildNode pure interface.
• Object types implementing this pure interface: CharacterData, and Element.