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This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The ChildNode.before method inserts a set of Node or DOMString objects in the children list of this ChildNode's parent, just before this ChildNode. DOMString objects are inserted as equivalent Text nodes.

Syntax

[Throws, Unscopable] 
void ChildNode.before((Node or DOMString)... nodes);

Parameters

nodes
A set of Node or DOMString objects to insert.

Exceptions

Examples

Inserting an element

var parent = document.createElement("div");
var child = document.createElement("p");
parent.appendChild(child);
var span = document.createElement("span");

child.before(span);

console.log(parent.outerHTML);
// "<div><span></span><p></p></div>"

Inserting text

var parent = document.createElement("div");
var child = document.createElement("p"); 
parent.appendChild(child);

child.before("Text"); 

console.log(parent.outerHTML);
// "<div>Text<p></p></div>"

Inserting an element and text

var parent = document.createElement("div");
var child = document.createElement("p"); 
parent.appendChild(child); 
var span = document.createElement("span");

child.before(span, "Text"); 

console.log(parent.outerHTML);
// "<div><span></span>Text<p></p></div>"

ChildNode.before() is unscopable

The before() method is not scoped into the with statement. See Symbol.unscopables for more information.

with(node) { 
  before("foo");
}
// ReferenceError: before is not defined 

Polyfill

You can polyfill the before() method in Internet Explorer 9 and higher with the following code:

// from: https://github.com/jserz/js_piece/blob/master/DOM/ChildNode/before()/before().md
(function (arr) {
  arr.forEach(function (item) {
    if (item.hasOwnProperty('before')) {
      return;
    }
    Object.defineProperty(item, 'before', {
      configurable: true,
      enumerable: true,
      writable: true,
      value: function before() {
        var argArr = Array.prototype.slice.call(arguments),
          docFrag = document.createDocumentFragment();
        
        argArr.forEach(function (argItem) {
          var isNode = argItem instanceof Node;
          docFrag.appendChild(isNode ? argItem : document.createTextNode(String(argItem)));
        });
        
        this.parentNode.insertBefore(docFrag, this);
      }
    });
  });
})([Element.prototype, CharacterData.prototype, DocumentType.prototype]);

Specification

Specification Status Comment
DOM
The definition of 'ChildNode.before()' in that specification.
Living Standard Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic support
Experimental
Chrome Full support 54Edge Full support 17Firefox Full support 49IE No support NoOpera Full support 39Safari No support NoWebView Android Full support 54Chrome Android Full support 54Edge Mobile No support NoFirefox Android Full support 49Opera Android Full support 39Safari iOS No support NoSamsung Internet Android Full support 6.0

Legend

Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

See also

ドキュメントのタグと貢献者

このページの貢献者: fscholz, dima74, stevenwdv, Permutator, zhi.lin, jszhou, jpmedley
最終更新者: fscholz,