ng-change
动态监听用户输入变化，弹出1
<input type="text" ng-change="show()" ng-model="a" name="">
ng-blur
<input type="text" ng-blur="show()" ng-model="a" name="">
ng-focus
<input type="text" ng-focus="show()" ng-model="a" name="">
ng-keydown
<input type="text" ng-keydown="show()" ng-model="a" name="">
ng-keyup
<input type="text" ng-keyup="show()" ng-model="a" name="">
ng-keypress
<input type="text" ng-keypress="show()" ng-model="a" name="">
