如何检查AngularJS中是否指定了伪指令的方法参数？ [英] How to check if a method argument of a directive is specified in AngularJS?
问题描述
我创建了一个包含按钮的自定义指令。此按钮从callback属性指定的父作用域调用方法。
<！DOCTYPE html&
< html ng-app =app>
< head>
< title>简单指令< / 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 ：'+ param）;
}
}）
app.directive（'myDirective'，function（）{
var ret = {
restrict ：'E'，
scope：{
user：'@'，
callback：'&'//绑定范围内的函数
}，
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 =catcallback =doSomething（userData）>< / my-directive>
< my-directive user =dogcallback =doSomething（userData）>< / my-directive>
< my-directive user =pig>< / my-directive>
< / body>
< / html>
我的问题是：
我控制按钮内部模板的可见性？如果回调属性没有在自定义标签中指定，我想隐藏它（见第3个my-directive标签）。
当我检查typeof的回调，我总是得到'function'和angular.isDefined（...）也返回true。
如果未设置属性，则使用& ;?返回undefined。
'&'=始终定义回调函数。 >
'& ;?'=回调函数仅在html模板中定义了属性时定义。
code> bindToController：{
callback：'& ;?'
}，
controller：function（）{
if（this.callback === undefined）{
//未定义属性callback
}
}
注意：在Angular 1.4.8中工作。我不知道它是否在旧版本中工作。
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>
My question is:
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.
Using '&?' returns undefined if the attribute has not been set.
'&' = callback function is defined always.
'&?' = callback function is defined only when attribute is defined in html template.
bindToController: {
callback: '&?'
},
controller: function() {
if (this.callback === undefined) {
// attribute "callback" was not defined
}
}
Note: Works in Angular 1.4.8. I'm not sure if it works in older versions.
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