Interface Deferred<TR, TJ, TN>

``

3.0

​ ````Since the jQuery.get method returns a jqXHR object, which is derived from a Deferred object, we can rejection handlers using the .catch method.

$.get( "test.php" )
.then( function() {
alert( "$.get succeeded" );
} )
.catch( function() {
alert( "$.get failed!" );
} );

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter resolve value:

var defer = $.Deferred(),
filtered = defer.pipe(function( value ) {
return value * 2;
});
​
defer.resolve( 5 );
filtered.done(function( value ) {
alert( "Value is ( 2*5 = ) 10: " + value );
});

​ ````Filter reject value:

var defer = $.Deferred(),
filtered = defer.pipe( null, function( value ) {
return value * 3;
});
​
defer.reject( 6 );
filtered.fail(function( value ) {
alert( "Value is ( 3*6 = ) 18: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter reject value:

var defer = $.Deferred(),
filtered = defer.pipe( null, function( value ) {
return value * 3;
});
​
defer.reject( 6 );
filtered.fail(function( value ) {
alert( "Value is ( 3*6 = ) 18: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter resolve value:

var defer = $.Deferred(),
filtered = defer.pipe(function( value ) {
return value * 2;
});
​
defer.resolve( 5 );
filtered.done(function( value ) {
alert( "Value is ( 2*5 = ) 10: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter resolve value:

var defer = $.Deferred(),
filtered = defer.pipe(function( value ) {
return value * 2;
});
​
defer.resolve( 5 );
filtered.done(function( value ) {
alert( "Value is ( 2*5 = ) 10: " + value );
});

​ ````Filter reject value:

var defer = $.Deferred(),
filtered = defer.pipe( null, function( value ) {
return value * 3;
});
​
defer.reject( 6 );
filtered.fail(function( value ) {
alert( "Value is ( 3*6 = ) 18: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter reject value:

var defer = $.Deferred(),
filtered = defer.pipe( null, function( value ) {
return value * 3;
});
​
defer.reject( 6 );
filtered.fail(function( value ) {
alert( "Value is ( 3*6 = ) 18: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.6

1.7

​ Deprecated since 1.8. Use ``.

Cause: The .pipe() method on a jQuery.Deferred object was deprecated as of jQuery 1.8, when the .then() method was changed to perform the same function.

Solution: In most cases it is sufficient to change all occurrences of .pipe() to .then(). Ensure that you aren't relying on context/state propagation (e.g., using this) or synchronous callback invocation, which were dropped from .then() for Promises/A+ interoperability as of jQuery 3.0.

​ ````Filter resolve value:

var defer = $.Deferred(),
filtered = defer.pipe(function( value ) {
return value * 2;
});
​
defer.resolve( 5 );
filtered.done(function( value ) {
alert( "Value is ( 2*5 = ) 10: " + value );
});

​ ````Chain tasks:

var request = $.ajax( url, { dataType: "json" } ),
chained = request.pipe(function( data ) {
return $.ajax( url2, { data: { user: data.userId } } );
});
​
chained.done(function( data ) {
// data retrieved from url2 as provided by the first request
});

``

1.5

​ ````Use the target argument to promote an existing object to a Promise:

// Existing object
var obj = {
hello: function( name ) {
alert( "Hello " + name );
}
},
// Create a Deferred
defer = $.Deferred();
​
// Set object as a promise
defer.promise( obj );
​
// Resolve the deferred
defer.resolve( "John" );
​
// Use the object as a Promise
obj.done(function( name ) {
obj.hello( name ); // Will alert "Hello John"
}).hello( "Karl" ); // Will alert "Hello Karl"

``

1.5

​ ````Create a Deferred and set two timer-based functions to either resolve or reject the Deferred after a random interval. Whichever one fires first "wins" and will call one of the callbacks. The second timeout has no effect since the Deferred is already complete (in a resolved or rejected state) from the first timeout action. Also set a timer-based progress notification function, and call a progress handler that adds "working..." to the document body.

function asyncEvent() {
var dfd = jQuery.Deferred();
​
// Resolve after a random interval
setTimeout(function() {
dfd.resolve( "hurray" );
}, Math.floor( 400 + Math.random() * 2000 ) );
​
// Reject after a random interval
setTimeout(function() {
dfd.reject( "sorry" );
}, Math.floor( 400 + Math.random() * 2000 ) );
​
// Show a "working..." message every half-second
setTimeout(function working() {
if ( dfd.state() === "pending" ) {
dfd.notify( "working... " );
setTimeout( working, 500 );
}
}, 1 );
​
// Return the Promise so caller can't change the Deferred
return dfd.promise();
}
​
// Attach a done, fail, and progress handler for the asyncEvent
$.when( asyncEvent() ).then(
function( status ) {
alert( status + ", things are going well" );
},
function( status ) {
alert( status + ", you fail this time" );
},
function( status ) {
$( "body" ).append( status );
}
);

``

1.8

​ ````Since the jQuery.get method returns a jqXHR object, which is derived from a Deferred object, we can attach handlers using the .then method.

$.get( "test.php" ).then(
function() {
alert( "$.get succeeded" );
}, function() {
alert( "$.get failed!" );
}
);

​ ````Filter the resolve value:

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>deferred.then demo</title>
<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
</head>
<body>
​
<button>Filter Resolve</button>
<p></p>
​
<script>
var filterResolve = function() {
var defer = $.Deferred(),
filtered = defer.then(function( value ) {
return value * 2;
});
​
defer.resolve( 5 );
filtered.done(function( value ) {
$( "p" ).html( "Value is ( 2*5 = ) 10: " + value );
});
};
​
$( "button" ).on( "click", filterResolve );
</script>
​
</body>
</html>