<form class="register ng-scope" ng-app="regist_app" onsubmit="registSumbitValid()" ng-controller="regist_control">

 <div class="item">
  <input id="username" name="username" placeholder="请填写11位手机号码" class="input-item" ng-model="username" >
  <span class="warnning">{{username_error}}</span>
 </div>
</form>

var usernameValid=false;
var registApp =angular.module('regist_app',[]);
registApp.controller('regist_control',function($scope){
 $scope.username="";
 $scope.username_error="";
 var phonePattern=/\D+/;
 /*验证号码输入*/
 $scope.$watch('username',function(newValue,oldValue){
  if(newValue!=oldValue){
   if(newValue==""){
    $scope.username_error="号码不能为空";
    usernameValid=false;
   }
   else if(phonePattern.test(newValue)){
    $scope.username_error='只能输入数字';
    usernameValid=false;
   }
   else if(newValue.length!=11){
    $scope.username_error='格式不正确，请输入11位号码';
    usernameValid=false;
   }else if(newValue.length==11){
    $scope.username_error="";
    usernameValid=true;
   }
  }
 });
}