1. $parse service
The $parse service can convert an expression into a function. This function can be called, and the arguments are a context object, usually scoped.
In addition, the function returned by the $parse expression has an assign property. This assign property is also a function that can be used to change the value of this expression in a given context.
<div my-attr="" my-directive>testing</div>
('myDirective',function($log, $parse) {
return function(scope, elem, attrs) {
//Parse "my-attr attribute value into a function" var model = $parse();
//Model is now a function, which can be called to get the value of the expression //The following line of code will output the value in the scope $(model(scope));
('click',function(){
//'' is also a function, which is used to update the value of an expression (scope,'New name');
scope.$apply();
})
}
});The above example fully demonstrates why we need the $parse service. If the property value is name, then we can do nothing to use $parse, just scope[]. But in the example above, square brackets don't work.
2. $eval service
$eval is a method in scope scope, which will execute an expression in the current scope and return the result:
= 1;
= 2;
scope.$eval('a+b'); // 3