GM xmlhttpRequest

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The correct title of this article is GM_xmlhttpRequest. The substitution or omission of an _ is due to technical restrictions.


[edit] Description

This API method provides access to the chrome-privileged XMLHttpRequest object. This means that it is possible to issue requests to domains other than that of the current page.

Additional reference may be found at:

Examples | Notes

[edit] Syntax

GM_xmlhttpRequest( details )

Value: Function
Returns: Nothing, details Object
Compatibility: Greasemonkey 0.2.5+
details Object
Properties Event Handler Callbacks
method onload
url onreadystatechange
headers onerror
overrideMimeType
data
  • All properties and event handler callbacks are optional except method and url.

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[edit] Properties

[edit] method

Value: String
Usage: details.method = "GET"';

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[edit] url

Value: String
Usage: details.url = "http://www.greasespot.net/";

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[edit] headers

Value: Object
Usage: details.headers = {"User-Agent":"Mozilla/5.0"};
  • The headers property is an object which is typically used to override the default browser generated headers, also known as atoms. It should contain the atom-value pairs of the headers to send.[2]

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[edit] overrideMimeType

Value: String
Compatibility: Greasemonkey 0.6.8+
Usage: details.overrideMimeType = "text/html; charset=ISO-8859-1";
  • While each character set name may have multiple aliases defined, there may be a preferred name which can be found at IANA

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[edit] data

Value: String
Usage: details.data = null; /* some code */ if (details.data) { /* some code */ }

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[edit] Event Handler Callbacks

[edit] onload

Usage: details.onload = function (response) { /* some code */ };
Returns: Nothing, response Object

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[edit] onreadystatechange

Usage: details.onreadystatechange = function (response) { /* some code */ };
Returns: Nothing, response Object

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[edit] onerror

Usage: details.onerror = function (response) { /* some code */ };
Returns: Nothing, response Object

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response Object
Properties
status readyState responseText finalUrl
statusText responseHeaders

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[edit] Properties

[edit] status

Value: Number
Usage: if (response.status == 200) { /* some code */ }

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[edit] statusText

Value: String
Usage: if (response.statusText == "OK") { /* some code */ }

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[edit] readyState

Value: Number
Usage: if (response.readyState == 4) { /* some code */ }

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[edit] responseText

Value: String
Usage: alert(response.responseText);

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[edit] responseHeaders

Value: String
Usage: if (response.responseHeaders) { /* some code */ }
  • The responseHeaders is the string representation of response headers returned by XMLHTTPRequest.getAllResponseHeaders().

[edit] finalUrl

Value: String
Compatibility: Greasemonkey 0.8.0+
Usage: if (response.finalUrl) { /* some code */ }

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[edit] Examples 

 GM_xmlhttpRequest({
   method:"GET",
   url:"http://www.greasespot.net/",
   headers:{
     "User-Agent":"Mozilla/5.0",            // Recommend using navigator.userAgent when possible
     "Accept":"text/xml"
   },
   onload:function(response) {
     alert([
       response.status,
       response.statusText,
       response.readyState,
       response.responseHeaders,
       response.responseText,
       response.finalUrl
     ].join("\n"));
   }
 });

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[edit] Notes

[1]Some users have reported problems with international character sets. See these mailing list threads

Resolved: Greasemonkey exposed the overrideMimeType method to allow changing of the desired charset.

[2]Some header atoms may not actually work through GM_xmlhttpRequest. The Referer atom is one that is known to be recognized but appears to be content filtered by the browser. This may be due to security restrictions to keep user scripts from doing unsafe things.

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Retrieved from "http://wiki.greasespot.net/GM_xmlhttpRequest"
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