AngularJS - 基于表达式隐藏/显示指令输出

Question

我想从自定义指令输出一些标记,但仅当模型包含一些文本时.

我几乎就在那里,但我不太确定如何在模型改变时打开/关闭模板,如果这甚至是最有效的方式.

这是标记:

<div data-ng-controller="test">
<div class="box">
    <input type="text" id="search" maxlength="75" data-ng-model="keywords" />
</div>
<searched data-ng-model="keywords"></searched>
</div>

JS:

var app = angular.module('myApp', []);

app.directive('searched', function(){
    return {
        restrict: 'E',
        replace: true,
        scope: {
            keywords: '=ngModel'
        },
        template: '<span><span class="field">You searched for:</span> {{ keywords }}</span> ',
        link: function(scope, element, attrs) {
            scope.$watch('keywords', function(newVal, oldVal){
                if(newVal === null) {
                    // Output nothing!
                } else {
                    // Output Template as normal.
                }
            }, true);

        }
    };
});

app.controller("test", ['$scope', function($scope) {
    $scope.keywords = null;
}]);

并举例说明JSFiddle

Answer 1

如果我理解你想做什么,最简单的方法就是用ng-show.然后你甚至不需要$watch(或链接功能)

app.directive('searched', function(){
    return {
        restrict: 'E',
        replace: true,
        scope: {
            keywords: '=ngModel'
        },
        template: '<span ng-show="keywords.length > 0"><span class="field">You searched for:</span> {{ keywords }}</span> '
    };
});

更新了小提琴