In my directive, I am passing a function to a plugin which will use it with a specified value. Let's simplify things by ignoring data changes:
angular.module('some.directives', [])
.directive('myDirective', [,
function () {
return {
restrict: 'EAC',
scope: {
value: '@', // some value
fun: '&' // the function
},
link: function(scope, element, attrs) {
ThePlugin.thisIsTheVal(scope.value);
ThePlugin.thisIsTheFun(scope.fun);
}
};
}
]);
The issue arises when the fun attribute is not defined or if the parent scope does not have the specified function. In such cases, ThePlugin defaults to executing angular.noop, provided by AngularJS.
I need to distinguish between a real undefined and an undefined function. How can I determine if the calling scope actually contains the required function?
A possible solution could involve checking the function against the target value and returning undefined only if the result is also undefined:
ThePlugin.thisIsTheFun(function() {
if (scope.fun(scope.value) === undefined) {
return scope.fun;
}
return undefined;
});
This workaround may introduce inconsistencies as the fun function might be designed to return undefined in the future for valid reasons.