angularjs 中的$watch 用来监控变量的变化,并做出改变.
在 ionic 中也有这个需求,这有个小小的坑.

<label class="item item-input">
     <i class="icon ion-search placeholder-icon"></i>
     <input type="text" placeholder="Search" ng-model="user">
     </label>
            {{user}}
            {{updated}}

  $scope.updated = -1;
  $scope.$watch('user.name', ()->
    console.log $scope.user
    $scope.updated++;
  , true
  );

用 angular 这样的写法,死活不行.
google 了下,需要把watch的内容放在一个父元素中.js 代码如下:

  $scope.user = {name: "sss"}
  $scope.updated = -1;

  $scope.$watch('user.name', ()->
    console.log $scope.user
    $scope.updated++;
  , true
  );

html 代码

<div class="list list-inset">
    <label class="item item-input">
        <i class="icon ion-search placeholder-icon"></i>
        <input type="text" placeholder="Search" ng-model="user.name">
    </label>
{{user}}
{{updated}}
</div>

本文参考
http://forum.ionicframework.com/t/why-does-this-scope-watch-not-work/9430