Angular 1.5 Component Bindings: Check if Callback is Present
The simplest way would to check if the attribute is defined. In your controller inject $attrs and then you can do:
if( $attrs.onRemove ) { //Do something }Using the & binding angular will wrap the function in order to keep references to the original $scope of the passed method, even if is not defined.
Execute the function onRemove on component allow to get if a function was passed in parameter. So you can use ng-if="$ctrl.onRemove()"
component('contactList', {template: `<div ng-repeat="c in $ctrl.contacts"> {{c.name}} <div ng-click="$ctrl.onRemove()({contact: c})" ng-if="$ctrl.onRemove()">Remove</div> </div>`,bindings: { contacts: '<', onRemove: '&'},controller: function() { console.log(this.onRemove); console.log(this.onRemove());}})
another option is to define the callback as optional by adding a question mark in the binding definition:onRemove: '&?'
text from the documentation: All 4 kinds of bindings (@, =, <, and &) can be made optional by adding ? to the expression. The marker must come after the mode and before the attribute name. See the Invalid Isolate Scope Definition error for definition examples.