document.getElementById

Sumário

Retorna a referência do elemento através do seu ID.

Sintaxe

elemento = document.getElementById(id);

onde

  • elemento é uma referência a um objeto Element, ou null se um elemento com o ID especificado não estiver contido neste documento.
  • id é uma string sensível a maiúsculas e minúsculas representando o ID único do elemento sendo procurado.

Exemplo

<!DOCTYPE html>
<html>
<head>
  <title>getElementById example</title>
  <script>
  function changeColor(newColor) {
    var elem = document.getElementById("para1");
    elem.style.color = newColor;
  }
  </script>
</head>
<body>
  <p id="para1">Some text here</p>
  <button onclick="changeColor('blue');">blue</button>
  <button onclick="changeColor('red');">red</button>
</body>
</html>

Notas

New users should note that the capitalization of 'Id' in the name of this method must be correct for the code to function - 'getElementByID' does not work, however natural it may seem.

If there is no element with the given id, this function returns null. Note that the ID parameter is case-sensitive, so document.getElementById("Main") will return null instead of the element <div id="main"> because "M" and "m" are different for the purposes of this method.

Elements not in the document are not searched by getElementById. When creating an element and assigning it an ID, you have to insert the element into the document tree with insertBefore or a similar method before you can access it with getElementById:

var element = document.createElement("div");
element.id = 'testqq';
var el = document.getElementById('testqq'); // el will be null!

Non-HTML documents. The DOM implementation must have information that says which attributes are of type ID. Attributes with the name "id" are not of type ID unless so defined in the document's DTD. The id attribute is defined to be of ID type in the common cases of XHTML, XUL, and other. Implementations that do not know whether attributes are of type ID or not are expected to return null.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 1.0 (1.7 or earlier) 5.5 7.0 1.0
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 1.0 1.0 (1.0) 6.0 6.0 1.0

Specification

getElementById was introduced in DOM Level 1 for HTML documents and moved to all documents in DOM Level 2.

See also

  • document reference for other methods and properties you can use to get references to elements in the document.
  • xml:id - has a utility method for allowing getElementById to obtain 'xml:id' in XML documents (such as returned by Ajax calls)

Document Tags and Contributors

Contributors to this page: YgorFranca, willian
Última atualização por: willian,