How to use scope in Angular scope

This article mainly introduces the specific use of Angular scope. The editor thinks it is quite good. Now I will share it with you and give it as a reference. Let’s follow the editor and take a look.

Scope (scope) is the link between HTML (view) and JavaScript (controller).

Scope is an object with available methods and properties.

Scope can be applied to views and controllers.

$rootScope

Every AngularJs application has a root scope by default - $rootScope. The root scope is at the top and serves as the parent scope of other scopes. , can be used throughout the application.

$scope

scope (scope) corresponds to the Model of the MVC mode. It is the link between HTML (view) and JavaScript (controller). It can Applies to views and controllers.

Scope is the context in which the expression is executed. At the same time, the scope is also an object with available methods and properties.

1. Value acquisition and assignment of variables

<p ng-controller="parentCtrl">
 <span>{{number}}</span>
 <p ng-controller="childCtrl">
  <span>{{number}}</span>
  <button ng-click="number = number +1">增加</button>
 </p>
</p>

function parentCtrl($scope){
 $scope.number = 1;
}
function childCtrl($scope){ 
}

Effect:

Two 1s are displayed on the interface, but When we click the button, the data in the childCtrl scope changes, but the data in the parentCtrl scope does not change

Analysis:

①The childCtrl scope inherits the parentCtrl scope ( Similar to JavaScript's prototype chain inheritance), so the childCtrl scope can access the content of parentCtrl.
②After clicking the button, a number basic type variable will be created in the childCtrl scope. When childCtrl already has a basic type variable, it will not access the prototype chain.

Solution:

①You can use $parent to specify the upper-level scope change

 <p ng-controller="parentCtrl">
  <span>{{number}}</span>
  <p ng-controller="childCtrl">
   <span>{{number}}</span>
   <button ng-click="$parent.number = number +1">增加</button>
  </p>
 </p>

②Use reference type variables, both inner and outer scopes The reference of the data object, modifying the properties of the object, still refers to the same variable.

 <p ng-controller="parentCtrl">
  <span>{{data.number}}</span>
  <p ng-controller="childCtrl">
   <span>{{data.number}}</span>
   <button ng-click="data.number = data.number +1">增加</button>
  </p>
 </p>
 
 function parentCtrl($scope){
  $scope.data.number = 123&#39;;
 }
 function childCtrl($scope){
  
 }

ng-if, ng-repeat, ng-switch, ng-include and other instructions will also generate new scopes

2. Scope in Directive

.directive("myDirective", function () {
return {
 restrict: "AE",
 scope: {
  name: '@myName',
  age: '=',
  changeAge: '&changeMyAge'
 },
 replace: true,
 template: "<p class=&#39;my-directive&#39;>" +
  "我的名字是：<span ng-bind=&#39;name&#39;></span><br/>" +
  "我的年龄是：<span ng-bind=&#39;age&#39;></span><br/>" +
  "在这里修改名字：<input type=&#39;text&#39; ng-model=&#39;name&#39;><br/>" +
  "<button ng-click=&#39;changeAge()&#39;>修改年龄</button>" +
  " </p>"
}

①scope: false

When scope is set to false, the directive we create shares the same model model with the parent scope (actually the same scope), so modify it in the directive Model data, which will be reflected in the model of the parent scope.

②scope: true

When scope is set to true, we create a new scope, but this scope is an inherited parent scope; it can be understood this way, our new scope The created scope is a new scope, but during initialization, the properties and methods of the parent scope are used to fill our new scope. It is not the same scope as the parent scope.

③scope: {}

@ This is a prefix identifier of a single binding

<p my-directive my-name="{{name}}"></p>

The name of the attribute should use - to connect the two words, because it is data Single item binding requires binding data by using {{}}.

= This is a two-way data binding prefix identifier

<p my-directive age="age"></p>

Two-way binding of data must be achieved through the = prefix identifier, so {{}} cannot be used.

& This is a prefix identifier of a binding function method

<p my-directive change-my-age="changeAge()"></p>

The name of the attribute should be connected with multiple words -.

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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