角度指令链接函数中“ attrs”参数的用途是什么

Question

Considering this directive :

.directive('myDirective', function(httpRequestTracker) {
    return {
        restrict: 'EA',
        scope: {
            myvar: "=",
        },
        link: function($scope, elem, attrs) {
            console.log($scope.myvar, attrs.myvar);
        }
    };
})

and this JS console output :

> undefined undefined // if no attribute

> value value // if attribute value = "value"

What is the use of the attr parameter of the link function ? What is the difference with $scope ?

Thanks

Answer 1

attrs is just a raw list of attributes on a directive
scope is more sophisticated, you can use three different operators to populate it with values:

• = evaluates expression in HTML, and may contain objects
• @ interprets value passed as string. always.
• & gives you access to functions defined on parent scope

Answer 2

I know I'm quite late to the party, but for posterity's sake, the most crucial difference to me is that using scope: {...} in the directive's definition object (not the link function signature) creates an isolate scope within the directive element, whereas omitting the scope property altogether and manually retrieving values from attrs does not. There are plenty of cases where, for whatever reason, you don't want to make a new scope but you still need the value of some attribute.