Ph0en1x Ph0en1x - 2 years ago 201
Javascript Question

angular trigger changes with $watch vs ng-change, ng-checked, etc

Currently we could monitor data changes with several ways. We could trigger model changes with

and we could add directives to elements and bind some actions to it.

It's a little bit confusing in many cases, so I'm curious, which is pro and cons of each variant and when should we use
binding, and when directives like

Answer Source

Both $watch and ngChange have totally different usages:

Lets say you have a model defined on a scope:

$scope.myModel = [

Now if you want to do something whenever any changes happen to myModel you would use $watch:

$scope.$watch("myModel", function(newValue, oldValue){
    // do something

ngChange is a directive that would evaluate given expression when user changes the input:

<select ng-model="selectedOption" ng-options="option for option in options" 

In short, you would normally bind ngChange to some HTML element. While $watch is for the models.

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