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AngularJS ng-required用法及代码示例

AngularJS中的ng-required指令用于指定HTML元素的必需属性。仅当ng-required指令中的表达式返回true时,才需要表单中的输入字段。 <input>,<select>和<textarea>支持。

用法:

<element ng-required="expression"> Contents... </element> 

范例1:本示例使用ng-required指令将表单标签的输入文本字段设置为必填。


<!DOCTYPE html> 
<html> 
  
<head> 
    <title>ng-required Directive</title> 
      
    <script src= 
"https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js"> 
    </script> 
  
    <style> 
        .req { 
            font-size:90%; 
            font-style:italic; 
            color:red; 
        } 
    </style> 
</head> 
  
<body style="text-align:center"> 
      
    <h1 style="color:green">GeeksforGeeks</h1> 
    <h2>ng-required Directive</h2> 
      
    <div ng-app="app" ng-controller="myCtrl">                  
        <form name="myForm"> 
            <p>Enter Your Name:<br/> 
                <span> 
                    <input type="text" name="name"
                    ng-model="Name" ng-required ="true" /> 
                </span> 
            </p> 
              
            <span ng-show="myForm.name.$invalid" class="req"> 
                This is the required field. 
            </span> 
        </form> 
    </div> 
      
    <script> 
        var app = angular.module("app", []);          
        app.controller("myCtrl", function($scope) {  
            $scope.Name = ""; 
        }); 
    </script> 
</body> 
  
</html>                    

输出:
输入名称之前:
ngrequired
输入名称后:
ngrequired

范例2:本示例使用ng-required指令在选中复选框后创建必填字段。

<!DOCTYPE html> 
<html> 
  
<head> 
    <title>ng-required Directive</title> 
      
    <script src= 
"https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js"> 
    </script> 
</head> 
  
<body ng-app="app"style="text-align:center"> 
      
    <h1 style="color:green">GeeksforGeeks</h1> 
    <h2>ng-required Directive</h2>                      
      
    <div ng-controller="geek" style="font-family:arial;">  
        <form name="myform"> 
            <label for="requiredValue"> 
                Is Required:
            </label> 
              
            <input type="checkbox" ng-model="requiredValue"
                        id="required" /> 
            <br><br> 
              
            <label for="input">Enter Name:</label> 
              
            <input type="text" ng-model="model" id="input"
                name="input" ng-required="requiredValue" /> 
            <br>          
              
            <p style="color:red;"
                    ng-show='myform.input.$error.required'> 
                Name is required 
            </p>  
        </form>  
    </div>      
      
    <script>      
        var app = angular.module('app', [])  
        app.controller('geek', ['$scope', function($scope) {  
            $scope.requiredValue = true;  
        }]);  
    </script>  
</body> 
  
</html>                    

输出:
在选中复选框之前:
ngrequired
选中复选框后:
ngrequired



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注:本文由纯净天空筛选整理自Vishal Chaudhary 2大神的英文原创作品 AngularJS | ng-required Directive。非经特殊声明,原始代码版权归原作者所有,本译文的传播和使用请遵循“署名-相同方式共享 4.0 国际 (CC BY-SA 4.0)”协议。