Question

我试图检查字符串的长度，但它不起作用，有人可以帮我找到我做错的事吗？

HTML

<div ng-app="myApp" ng-controller="formCtrl"> 
<form novalidate> First Name:<br> <input type="text" ng-model="user.firstName"><br>
<button ng-click="check()">RESET</button> 
</form> <p>form = {{user}}</p> </div>

JS是

var app = angular.module('myApp', []);
app.controller('formCtrl', function($scope) {

    $scope.check = function() {
        var arr = $scope.user;
        if (arr.length<=3){
            $scope.user="enjoy"
        }

    };
    $scope.check();
});

Answer 1

您尚未在控制器中声明$scope.user并调用check()功能。这样做会给你

TypeError: Cannot read property 'length' of undefined

因此您需要将$scope.user声明为

$scope.user= {
  firstName : ''
};

HTML

<div ng-app="myApp" ng-controller="formCtrl"> 
<form novalidate> First Name:<br> <input type="text" ng-model="user.firstName"><br>
<button ng-click="check()">RESET</button> 
</form> <p>form = {{user}}</p> </div>

所以你的控制器就像这样

angular.module('myApp',[]).controller('formCtrl', function($scope){
   $scope.user= {
     firstName : ''
   };

  $scope.check = function() {
    var arr = $scope.user.firstName;
    if (arr.length<=3){
        $scope.user.firstName="enjoy"
    }

  };
  $scope.check();
})

为简单起见，这里的解决方法是指向JSFIDDLE

的链接

角度js中的字符串长度

1 个答案: