Network Request

Creating a Network Request Object

var xmlHttp = new XMLHttpRequest();

The XMLHttpRequest object provides full access to HTTP, allowing you to send POST and HEAD requests, as well as standard GET requests. The XMLHttpRequest object can synchronously or asynchronously return a response from the web server in the form of text or a DOM document.

Definition

XMLHttpRequest.onreadystatechange = callBack

• Description

  Specifies the response processing function.

XMLHttpRequest.open(method, url, async, username, password)

• Description

  Initializes HTTP request parameters.

• Parameters
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  Parameter	Type	Mandatory	Description
  method	string	Yes	HTTP request method.
  url	string	Yes	Request body.
  async	boolean	No	Indicates whether the request should be executed asynchronously. The default value is true.
  username	string	No	User name for accessing the specified URL.
  password	string	No	Password for accessing the specified URL.

• Sample code
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  var xhr = new XMLHttpRequest();
  xhr.open('GET', '" + "test.php"+ "', true);

XMLHttpRequest.setRequestHeader(name, value)

• Description

  Sets the request header.

• Parameters
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  Parameter	Type	Mandatory	Description
  name	string	Yes	Name of the header to be set.
  value	string	Yes	Header value.

• Sample code
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  var xhr = new XMLHttpRequest();
  xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

XMLHttpRequest.send(body)

• Description

  Sends an HTTP request using the parameters passed to the open() method and an optional request body passed to the send method.

• Parameters
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  Parameter	Type	Mandatory	Description
  body	string/document	No	String or document.

• Sample code
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  var xhr = new XMLHttpRequest();
  xhr.open('POST', '" + "test.php"+ "', true);
  xhr.send("foo=bar&lorem=ipsum");

XMLHttpRequest.getAllResponseHeader()

• Description

  Returns all response headers.

XMLHttpRequest.getResponseHeader(header)

• Description

  Returns the value of the specified HTTP response header.

• Parameters
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  Parameter	Type	Mandatory	Description
  header	string	Yes	Name of the HTTP response header to be returned.

• Sample code
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  var client = new XMLHttpRequest();
  client.open("GET", "unicorns-are-teh-awesome.txt", true);
  client.send();
  client.onreadystatechange = function() {
    if(this.readyState == this.HEADERS_RECEIVED) {
      console.log(client.getResponseHeader("Content-Type"));
    }
  }

XMLHttpRequest.abort()

• Description

  Cancels the current request.

XMLHttpRequest.responseText

• Description

  Returns the response body (excluding the headers) received by the server so far, or an empty string if no data has been received.

XMLHttpRequest.responseXML

• Description

  Returns a Document object containing the XML retrieved by the request.

XMLHttpRequest.status

• Description

  Parses the response into XML and returns the result as a Document object.

XMLHttpRequest.statusText

• Description

  Returns the HTTP status code of a request.

XMLHttpRequest.readyState

• Description

  Describes the status of an HTTP request. It starts at 0 when the XMLHttpRequest object is created for the first time and progresses, reaching 4 once the full HTTP response has been received.

XMLHttpRequest.response

• Description

  Returns an ArrayBuffer, Blob, Document, or DOMString, depending on the value of XMLHttpRequest.responseType. The return value contains the entire response entity body.

XMLHttpRequest.responseType

• Description

  Defines enumerated values of the response type.

XMLHttpRequest.responseURL

• Description

  Returns a serialized response URL. If the URL is empty, an empty string is returned.

XMLHttpRequest.timeout

• Description

  Returns an unsigned long integer representing the maximum time, in milliseconds, that the request is allowed to take. If this time is exceeded, the request is automatically terminated.

XMLHttpRequest.withCredentials

• Description

  Returns a boolean value, indicating whether the cross-domain Access-Control request should contain authorization information, such as cookies or authorization headers.

XMLHttpRequest.overrideMimeType

• Description

  Overrides the MIME type returned by the server.