angular js一$watch監控屬性和對象

時間 2019-11-10

標籤 angular watch 監控屬性對象欄目 AngularJS 简体版

原文原文鏈接

$Watch：(監聽一個model,當一個model每次改變時，都會觸發第二個函數)javascript

$watch('watchFn',watchAction,deepWatch)html

watchFn：帶有Angular 表達式或者函數的字符串，它會返回被監控的數據模型的當前值。java

watchAction: 一個函數function(newValue,oldValue){},當watchFn 發生變化時會被調用數組

deepWatch:默認爲false,監聽數組的某個元素或者對象的屬性時設置爲true;app

監控一個屬性：函數

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
</head>
<body>
<div  ng-app="myApp" ng-controller="myCtrl">
    <form>
        <div class="form-group">
            <input  ng-model="name" />{{name}}
            <p>改變次數{{count}}</p>
        </div>
    </form>
</div>
<script src="http://cdn.static.runoob.com/libs/angular.js/1.4.6/angular.min.js"></script>
<script type="text/javascript">
   
    var app = angular.module('myApp', []);
    app.controller('myCtrl', function ($scope){
        $scope.name = '橘子';
        $scope.count = 0;
        $scope.$watch('name', function (newValue, oldValue) {
            $scope.count++;
            if($scope.count >5){
                $scope.name = '蘋果';
            }
        });
    });
</script>
</body>
</html>

監控一個對象（deepWidth爲true）spa

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
</head>
<body>
<div  ng-app="myApp" ng-controller="myCtrl">
    <form>
        <div class="form-group">
            <input  ng-model="Data.name" />{{Data.name}}
            <p>改變次數{{count}}</p>
        </div>
    </form>
</div>
<script src="http://cdn.static.runoob.com/libs/angular.js/1.4.6/angular.min.js"></script>
<script type="text/javascript">

    var app = angular.module('myApp', []);
    app.controller('myCtrl', function ($scope){
        $scope.Data = { name: '橘子' };
        $scope.count = 0;
        $scope.$watch('Data', function (newValue, oldValue) {
            if(newValue == oldValue)
            return;
            $scope.count++;
            if($scope.count >5){
                  $scope.Data.name = '蘋果';
            }
        }, true);
    });
</script>
</body>
</html>

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