如何检查是否在AngularJS指定指令的方法参数

如何检查是否在AngularJS指定指令的方法参数

本文介绍了如何检查是否在AngularJS指定指令的方法参数?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我已经创建了包含一个按钮自定义指令。该按钮调用由'回调'属性指定的父范围的方法。

I've created a custom directive which contains a button. This button calls a method from parent scope specified by 'callback' attribute.

<!DOCTYPE html>
<html ng-app="app">
<head>
    <title>Simple directive</title>

    <script src="js/lib/angular/angular.js"></script>

    <script type="text/javascript">
        var app = angular.module('app', []);

        app.controller('TestController', function($scope) {

            $scope.doSomething = function(param) {
                alert('Something called with: ' + param);
            }
        })

        app.directive('myDirective', function() {
            var ret = {
                restrict: 'E',
                scope: {
                    user: '@',
                    callback: '&'       // bound a function from the scope
                },
                template: '<div>Hello {{user}}<button ng-show="hasCallback()" ng-click="callback({userData: user})">Callback</button>',
                controller: function($scope) {
                    $scope.hasCallback2 = function() {
                        var t = typeof $scope.callback;
                        return t == 'function';
                    }

                    $scope.hasCallback = function() {
                        return angular.isDefined($scope.callback);
                    }
                }
            };
            return ret;
        });

    </script>
</head>

<body ng-controller="TestController">

<my-directive user="cat" callback="doSomething(userData)"></my-directive>
<my-directive user="dog" callback="doSomething(userData)"></my-directive>
<my-directive user="pig"></my-directive>

</body>

</html>

我的问题是:

我如何控制内部模板键的知名度?我想隐藏它,如果在​​自定义标签没有指定的回调属性(参见第3 MY-指示标记)。
当我检查的typeof回调,我总是得到功能和angular.isDefined(...)也返回true。

How can I control visibility of button inside template? I'd like to hide it if callback attribute not specified in custom tag (see 3rd my-directive tag).When I check typeof of callback, I always get 'function' and angular.isDefined(...) also returns true.

推荐答案

看着angularjs源$ C ​​$ C,我看到:

Looking at angularjs source code, I see this:

case '&':
    parentGet = $parse(attrs[attrName]);
    isolateScope[scopeName] = function(locals) {
         return parentGet(scope, locals);
    };
    break;

parentGet 是绑定的功能前pression。不幸的是,这是一个局部变量是只可透过封分配给 isolateScope [scopeName] 的功能。

The parentGet is the bound function expression. Unfortunately, this is a local variable which is only available to the function assigned to isolateScope[scopeName] via closure.

而不是试图找到一种方式来获得该变量,一个简单的办法就是检查 ATTRS 。尝试:

Instead of trying to find a way to get that variable, a simple solution is just to check the attrs. Try:

link: function(scope,elem,attrs) {

      scope.hasCallback = function() {
        return angular.isDefined(attrs.callback);
      }
    }

这篇关于如何检查是否在AngularJS指定指令的方法参数?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

09-02 01:42