The id global attribute defines an identifier (ID) which must be unique in the whole document. Its purpose is to identify the element when linking (using a fragment identifier), scripting, or styling (with CSS).
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This attribute's value is an opaque string: this means that web authors should not rely on it to convey human-readable information (although having your IDs somewhat human-readable can be useful for code comprehension, e.g. consider ticket-18659 versus r45tgfe-freds&$@).
id's value must not contain whitespace (spaces, tabs etc.). Browsers treat non-conforming IDs that contain whitespace as if the whitespace is part of the ID. In contrast to the class attribute, which allows space-separated values, elements can only have one single ID value.
Note: Using characters except ASCII letters, digits, '_', '-' and '.' may cause compatibility problems, as they weren't allowed in HTML 4. Though this restriction has been lifted in [[../../../../Glossary/HTML5|HTML5]], an ID should start with a letter for compatibility.
Specifications
| Specification | Status | Comment |
| HTML Living StandardThe definition of 'id' in that specification. | Living Standard | No change from latest snapshot, HTML 5.1 |
| HTML 5.1The definition of 'id' in that specification. | Recommendation | Snapshot of HTML Living Standard, no change from HTML5 |
| HTML5The definition of 'id' in that specification. | Recommendation | Snapshot of HTML Living Standard, now accept '_', '-' and '.' if not at the beginning of the id. It is also a true global attribute.
|
| HTML 4.01 SpecificationThe definition of 'id' in that specification. | Recommendation | Supported on all elements but <base>, <head>, <html>, <meta>, <script>, <style>, and <title>.
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Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
id
|
Chrome
Full support Yes |
Edge
Full support 12 |
Firefox Full support 32 Full support 32 No support ? — 32 Notes' |
IE
Full support Yes |
Opera
Full support Yes |
Safari
Full support Yes |
WebView Android
Full support Yes |
Chrome Android
Full support Yes |
Firefox Android Full support 32 Full support 32 No support ? — 32 Notes' |
Opera Android
Full support Yes |
Safari iOS
Full support Yes |
Samsung Internet Android
Full support Yes |
Legend
- Full support
- Full support
- See implementation notes.'
- See implementation notes.
See also
- All global attributes.
Element.idthat reflects this attribute.
id by Mozilla Contributors is licensed under CC-BY-SA 2.5.
