jQuery Deferred .promise() method
Last Updated :
16 Jul, 2020
This .promise() method in JQuery Returns a Promise object to be observed when certain type actions bounded to the collection, queued or not, are ended.
Syntax:
.promise([type][, target])
Parameters:
- type: This parameter specifies the type of queue which needed to be observed.
- target: This parameter specifies Object onto which the promise methods need to be attached.
Return Value: This method returns a dynamically generated Promise which is resolved once actions bounded to the collection, queued or not, have finished.
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 >
< title >
JQuery.when() method
</ title >
</ script >
</ head >
< body style = "text-align:center;" >
< h1 style = "color:green" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP" >
</ p >
< button onclick = "Geeks();" >
click here
</ button >
< p id = "GFG_DOWN" >
</ p >
< script >
var el_up = document.getElementById("GFG_UP");
el_up.innerHTML = "JQuery.when() method";
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 >
< title >
JQuery.when() method
</ title >
</ script >
</ head >
< body style = "text-align:center;" >
< h1 style = "color:green" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP" >
</ p >
< button onclick = "Geeks();" >
click here
</ button >
< p id = "GFG_DOWN" >
</ p >
< script >
var el_up = document.getElementById("GFG_UP");
el_up.innerHTML = "JQuery.when() method";
var def = $.Deferred();
function Geeks() {
$.when(def).done(function (x) {
$('#GFG_DOWN').append('when() method is executed.')
});
def.resolve();
}
</ script >
</ body >
</ html >
|
Output:
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