This JQuery.when() method in JQuery gives a way to execute callback functions depending on zero or more Thenable objects, which usually are Deferred objects that represent asynchronous events.
Syntax:
jQuery.when(deferreds)
- deferreds: This parameter specifies zero or more Thenable objects.
Parameters:
Return Value: This method returns a Promise.
There are two examples discussed below:
-
Example: In this example, the Deferred() is used to create a new object and after that then() method is called with notify and resolve method.
<!DOCTYPE HTML><html><head></script></head><bodystyle="text-align:center;"><h1style="color:green;">GeeksForGeeks</h1><p>JQuery.when() method</p><buttononclick="Geeks();">click here</button><pid="GFG_DOWN"></p><script>var def = $.Deferred();function Geeks() {$.when().then(function(a) {alert("when() method called this alert()." );});}</script></body></html>Output:
Before clicking on button:After clicking on button:
-
Example: In this example, the Deferred() method is used and the state of Deferred object is checked.
<!DOCTYPE HTML><html><head></script></head><bodystyle="text-align:center;"><h1style="color:green;">GeeksForGeeks</h1><p>JQuery.when() method</p><buttononclick="Geeks();">click here</button><pid="GFG_DOWN"></p><script>var def = $.Deferred();function Geeks() {$.when(def).done(function (x) {$('#GFG_DOWN').append('when() method is executed.')});def.resolve();}</script></body></html>Output: