HTML oninvalid事件用法及代码示例

当我们提交无效的元素时，将发生HTML DOM oninvalid事件。例如，输入字段是可提交的，并且设置了必填属性，则如果该字段为空，则该属性无效。

用法:

在HTML中：
```
<element oninvalid="myScript">
```

在JavaScript中：

object.oninvalid = function(){myScript};

在JavaScript中，使用addEventListener()方法：
```
object.addEventListener("invalid", myScript);
```

范例1：使用HTML。

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
      HTML DOM oninvalid Event 
  </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
        <form> 
            email:
            <input type="email"
                   oninvalid=""
                   name="email" 
                   required> 
            <br> 
            <input type="submit"
                   value="Submit"> 
        </form> 
    </center> 
</body> 
  
</html>

输出：

范例2：使用JavaScript。

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        HTML DOM oninvalid Event 
    </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
        <form> 
            Email:
            <input type="email" 
                   id="emailid"
                   name="email" 
                   required> 
            <br> 
            <input type="submit" 
                   value="Submit"> 
        </form> 
  
        <script> 
            document.getElementById( 
              "emailid").oninvalid = function() { 
                (GFGfun) 
            }; 
  
            function GFGfun() { 
                alert("Please fill out the required fields."); 
            } 
        </script> 
    </center> 
</body> 
  
</html>

输出：

范例3：使用addEventListener()方法：

<!DOCTYPE html> 
<html> 
  
<head> 
    <title> 
        HTML DOM oninvalid Event 
    </title> 
</head> 
  
<body> 
    <center> 
        <h1 style="color:green"> 
          GeeksforGeeks 
      </h1> 
        <h2> 
          HTML DOM oninvalid Event 
      </h2> 
  
        <form> 
            Email:
            <input type="email" 
                   id="emailid"
                   name="email"
                   required> 
            <br> 
            <input type="submit"
                   value="Submit"> 
        </form> 
  
        <script> 
            document.getElementById( 
                "emailid").addEventListener( 
                "invalid", GFGfun); 
  
            function GFGfun() { 
                alert( 
                    "Please fill out the required fields."); 
            } 
        </script> 
    </center> 
</body> 
  
</html>

输出：
之前：

后：

支持的浏览器：下面列出了HTML DOM oninvalid Event支持的浏览器：

谷歌浏览器
Internet Explorer 10.0
Firefox
苹果Safari
Opera

相关用法

注：本文由纯净天空筛选整理自Vijay Sirra大神的英文原创作品 HTML | DOM oninvalid Event。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。