ParentNode.prepend() - Web APIs 编辑

The ParentNode.prepend() method inserts a set of Node objects or DOMString objects before the first child of the ParentNode. DOMString objects are inserted as equivalent Text nodes.

Syntax

ParentNode.prepend(...nodesOrDOMStrings);

Parameters

nodesOrDOMStrings

A set of Node or DOMString objects to insert.

Return value

undefined.

Exceptions

• HierarchyRequestError: Node cannot be inserted at the specified point in the hierarchy.

Examples

Prepending an element

var parent = document.createElement("div");
var p = document.createElement("p");
var span = document.createElement("span");
parent.append(p);
parent.prepend(span);

console.log(parent.childNodes); // NodeList [ <span>, <p> ]

Prepending text

var parent = document.createElement("div");
parent.append("Some text");
parent.prepend("Headline: ");

console.log(parent.textContent); // "Headline: Some text"

Appending an element and text

var parent = document.createElement("div");
var p = document.createElement("p");
parent.prepend("Some text", p);

console.log(parent.childNodes); // NodeList [ #text "Some text", <p> ]

ParentNode.prepend() is unscopable

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

var parent = document.createElement("div");

with(parent) {
  prepend("foo");
}
// ReferenceError: prepend is not defined 

Polyfill

You can polyfill the prepend() method if it's not available:

// Source: https://github.com/jserz/js_piece/blob/master/DOM/ParentNode/prepend()/prepend().md
(function (arr) {
  arr.forEach(function (item) {
    if (item.hasOwnProperty('prepend')) {
      return;
    }
    Object.defineProperty(item, 'prepend', {
      configurable: true,
      enumerable: true,
      writable: true,
      value: function prepend() {
        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.insertBefore(docFrag, this.firstChild);
      }
    });
  });
})([Element.prototype, Document.prototype, DocumentFragment.prototype]);

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• ParentNode and ChildNode
• ParentNode.append()
• Node.appendChild()
• Node.insertBefore()
• ChildNode.before()
• Element.insertAdjacentElement()
• NodeList