Element.getAttribute() - Web APIs 编辑

The getAttribute() method of the Element interface returns the value of a specified attribute on the element. If the given attribute does not exist, the value returned will either be null or "" (the empty string); see Non-existing attributes for details.

Syntax

let 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.

Examples

<!-- example div in an html DOC -->
<div id="div1">Hi Champ!</div>

// in a console
const div1 = document.getElementById('div1');
//=> <div id="div1">Hi Champ!</div>

const exampleAttr= div1.getAttribute('id');
//=> "div1"

const align = div1.getAttribute('align')
//=> null

Description

Lower casing

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

Non-existing attributes

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; 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.

Retrieving nonce values

For security reasons, CSP nonces from non-script sources, such as CSS selectors, and  .getAttribute("nonce") calls are hidden.

let nonce =  script.getAttribute('nonce');
// returns empty string

Instead of retrieving the nonce from the content attribute, use the nonce property:

let nonce =  script.nonce;

Specifications

Browser compatibility

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