angular1.x $watch 监听的简单应用

$watch(watchExpression, listener, objectEquality);

watchExpression: 被监听的对象

listener: 包含3个值 newValue , oldValue, scope(可以引用一个作用域)

objectEquality:是否使用angular.equals方法比对


<html>
    <head>
        <meta charset="utf-8">
        <script src="http://cdn.static.runoob.com/libs/angular.js/1.4.6/angular.min.js">script>
    head>
    <body ng-app="ap"  >
        <div ng-controller="cl">
            <p>小框子1p>
            <input type="text" ng-model="input_value" /> 
            <p>小框子1的 $watch监听p>
            <span>{{dv}}span>
        div>
    body>
    <script> 
        var ap = angular.module("ap", [])
        .controller("cl", function($scope){   
             $scope.input_value = "我是一个初值";  
             $scope.$watch('input_value', function(newValue, oldValue) {  
                          $scope.dv=newValue;
                    });
            });
    script>
html>

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