XMLHttpRequest.getResponseHeader()
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 string indicating the name of the header you want to return the text value of.
Return value
A string 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 |
---|
XMLHttpRequest Standard # dom-xmlhttprequest-getresponseheader |
Browser compatibility
BCD tables only load in the browser
See also
- Using XMLHttpRequest
- HTTP headers
getAllResponseHeaders()
response
- Setting request headers:
setRequestHeader()