# deferred.catch()

所属分类：延迟对象 英文文档：deferred.catch()

## deferred.catch( failFilter )Returns: Promise

Description: Add handlers to be called when the Deferred object is rejected.

- #### version added: 3.0 deferred.catch( failFilter )

  - failFilter
    Type: Function()
    A function that is called when the Deferred is rejected.

`deferred.catch( fn )` is an alias to `deferred.then( null, fn )`. Read its page for more information.

## Example:

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

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