CODEWITHSUNDEEP
angularjs
Michael Lorton
Michael Lorton

Reputation: 44386

How can I $watch multiple values

My listener function depends on several values and I need to put $watch on each of them. I have thought of two ways:

scope.$watch(function() { return [calcOneValue(), calcTheOtherValue()]; },
             function(a) { return theListener(a[0], a[1]); });

or

scope.$watch(calcOneValue,
             function(a) { return theListener(a, calcTheOtherValue()); });

scope.$watch(calcTheOtherValue,
             function(a) { return theListener(calcOneValue(), a); });

Are these the right ways to do this? Is there a better third option I am missing?

Should I genericize this, make a function that takes a scope, an array of value functions and one, multi-parameter listener function? Or does such a function already exist? Or does $watch do this already?

Upvotes: 0

Views: 336

Answers (2)

New Dev
New Dev

Reputation: 49590

Angular has a built-in way to invoke the same function when any of specified expressions change - with $watchGroup:

$scope.$watchGroup(["foo", "bar"], function(newValues, oldValues){
   // do something when either $scope.foo or $scope.bar changes
});

Upvotes: 3

Scott
Scott

Reputation: 1690

You can deep watch an array by setting the third value of the call to true, and then put all your values in an array if you want.

 scope.$watch(myArray,function() { ...},true);

Upvotes: 0

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