自定义指令（Custom Directives）

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2023-12-01

AngularJS中使用自定义指令来扩展HTML的功能。自定义指令使用“指令”功能定义。自定义指令只是替换了激活它的元素。引导期间的AngularJS应用程序找到匹配的元素，并使用其自定义指令的compile（）方法执行一次活动，然后根据指令的范围使用自定义指令的link（）方法处理该元素。 AngularJS支持为以下类型的元素创建自定义指令。

Element directives - 当遇到匹配元素时，指令激活。
Attribute - 遇到匹配属性时激活指令。
CSS - 指令在遇到匹配的CSS样式时激活。
Comment - 当遇到匹配的注释时，指令激活。

了解自定义指令

定义自定义html标记。

<student name = "Mahesh"></student><br/>
<student name = "Piyush"></student>

定义自定义指令以处理上述自定义html标记。

var mainApp = angular.module("mainApp", []);
//Create a directive, first parameter is the html element to be attached.	  
//We are attaching student html tag. 
//This directive will be activated as soon as any student element is encountered in html
mainApp.directive('student', function() {
   //define the directive object
   var directive = {};
   //restrict = E, signifies that directive is Element directive
   directive.restrict = 'E';
   //template replaces the complete element with its text. 
   directive.template = "Student: <b>{{student.name}}</b> , 
      Roll No: <b>{{student.rollno}}</b>";
   //scope is used to distinguish each student element based on criteria.
   directive.scope = {
      student : "=name"
   }
   //compile is called during application initialization. AngularJS calls 
      it once when html page is loaded.
   directive.compile = function(element, attributes) {
      element.css("border", "1px solid #cccccc");
      //linkFunction is linked with each element with scope to get the element specific data.
      var linkFunction = function($scope, element, attributes) {
         element.html("Student: <b>"+$scope.student.name +"</b> , 
            Roll No: <b>"+$scope.student.rollno+"</b><br/>");
         element.css("background-color", "#ff00ff");
      }
      return linkFunction;
   }
   return directive;
});

定义控制器以更新指令的范围。这里我们使用name属性的值作为范围的子项。

mainApp.controller('StudentController', function($scope) {
   $scope.Mahesh = {};
   $scope.Mahesh.name = "Mahesh Parashar";
   $scope.Mahesh.rollno  = 1;
   $scope.Piyush = {};
   $scope.Piyush.name = "Piyush Parashar";
   $scope.Piyush.rollno  = 2;
});

例子 (Example)

<html>
   <head>
      <title>Angular JS Custom Directives</title>
   </head>
   <body>
      <h2>AngularJS Sample Application</h2>
      <div ng-app = "mainApp" ng-controller = "StudentController">
         <student name = "Mahesh"></student><br/>
         <student name = "Piyush"></student>
      </div>
      <script src = "https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js">
      </script>
      <script>
         var mainApp = angular.module("mainApp", []);
         mainApp.directive('student', function() {
            var directive = {};
            directive.restrict = 'E';
            directive.template = "Student: <b>{{student.name}}</b> , 
               Roll No: <b>{{student.rollno}}</b>";
            directive.scope = {
               student : "=name"
            }
            directive.compile = function(element, attributes) {
               element.css("border", "1px solid #cccccc");
               var linkFunction = function($scope, element, attributes) {
                  element.html("Student: <b>"+$scope.student.name +"</b> , 
                     Roll No: <b>"+$scope.student.rollno+"</b><br/>");
                  element.css("background-color", "#ff00ff");
               }
               return linkFunction;
            }
            return directive;
         });
         mainApp.controller('StudentController', function($scope) {
            $scope.Mahesh = {};
            $scope.Mahesh.name = "Mahesh Parashar";
            $scope.Mahesh.rollno  = 1;
            $scope.Piyush = {};
            $scope.Piyush.name = "Piyush Parashar";
            $scope.Piyush.rollno  = 2;
         });
      </script>
   </body>
</html>