The XMLHttpRequest
method getResponseHeader()
returns the string containing the text of a particular header's value. If there are multiple response headers with the same name, then their values are returned as a single concatenated string, where each value is separated from the previous one by a pair of comma and space. The getResponseHeader()
method returns the value as a UTF byte sequence.
Note: The search for the header name is case-insensitive.
If you need to get the raw string of all of the headers, use the getAllResponseHeaders()
method, which returns the entire raw header string.
Syntax
var myHeader = XMLHttpRequest.getResponseHeader(headerName);
Parameters
- headerName
- A
ByteString
indicating the name of the header you want to return the text value of.
Return value
A ByteString
representing the header's text value, or null
if either the response has not yet been received or the header doesn't exist in the response.
Example
In this example, a request is created and sent, and a readystatechange
handler is established to look for the readyState
to indicate that the headers have been received; when that is the case, the value of the Content-Type
header is fetched. If the Content-Type
isn't the desired value, the XMLHttpRequest
is canceled by calling abort()
.
var client = new XMLHttpRequest(); client.open("GET", "unicorns-are-teh-awesome.txt", true); client.send(); client.onreadystatechange = function() { if(this.readyState == this.HEADERS_RECEIVED) { var contentType = client.getResponseHeader("Content-Type"); if (contentType != my_expected_type) { client.abort(); } } }
Specifications
Specification | Status | Comment |
---|---|---|
XMLHttpRequest The definition of 'getResponseHeader()' in that specification. |
Living Standard | WHATWG living standard |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
getResponseHeader | Chrome Full support 1 | Edge Full support 12 | Firefox
Full support
1
| IE Full support 5 | Opera Full support 8 | Safari Full support 1.2 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android
Full support
4
| Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
- See implementation notes.
- See implementation notes.
See also
- Using XMLHttpRequest
- HTTP headers
getAllResponseHeaders()
response
- Setting request headers:
setRequestHeader()