Element.getAttribute()

摘要

getAttribute() 函式會回傳該網頁元素的屬性。 如果該屬性不存在，其回傳值會是null或 "" (空字串); 詳見 Notes 。

語法

var attribute = element.getAttribute(attributeName);

where

• attribute is a string containing the value of attributeName.
• attributeName is the name of the attribute whose value you want to get.

Example

var div1 = document.getElementById("div1");
var align = div1.getAttribute("align");

alert(align); // shows the value of align for the element with id="div1"

Notes

When called on an HTML element in a DOM flagged as an HTML document, getAttribute() lower-cases its argument before proceeding.

Essentially all web browsers (Firefox, Internet Explorer, recent versions of Opera, Safari, Konqueror, and iCab, as a non-exhaustive list) return null when the specified attribute does not exist on the specified element and this is what the current DOM specification draft specifies. The old DOM 3 Core specification, on the other hand, says that the correct return value in this case is actually the empty string, and some DOM implementations implement this behavior. The implementation of getAttribute in XUL (Gecko) actually follows the DOM 3 Core specification and returns an empty string. Consequently, you should use element.hasAttribute() to check for an attribute's existence prior to calling getAttribute() if it is possible that the requested attribute does not exist on the specified element.

Browser compatibility

Specification

• DOM Level 2 Core: getAttribute (introduced in DOM Level 1 Core)
• HTML 5: APIs in HTML documents