Home > Article > Web Front-end > How to determine whether the content of the text box in html is empty
How to determine whether the content of the text box in html is empty
- autoloadOriginal
- 2021-03-30 15:38:2811544browse
There are many ways to determine whether the content of the text box in the form is empty: 1. Judge through the php statement 2. Through js Statement judgment 3. Judge through html native statements.
1. Determine through the PHP statement:
Content in html:
<form action="submit.php" method="post"> <textarea name="text"></textarea> </form>
Content in php:
//submit.php <?php if(isset($_POST['text']) && strlen(trim($_POST['text']))>0) echo '不空'; else echo '空 '; ?>
2. Judgment by JS statement
<html>
<head>
<title>JS判断input是否为空</title>
<script>function op(){
if(document.getElementById("ip").value==""){
alert("input为空");
}else{
alert(document.getElementById("ip").value);
}
}
</script>
</head>
<body>
<input id="ip" onblur="op()" value="JS"/>
</body>
</html>3. Judgment by requiredattribute
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>表单</title>
</head>
<body>
<form action="" style="display: grid;" method="POST">
<div>
<label for="username">账号：</label>
<input type="text" id="username" required>
<!--required为必须填写数据-->
</div>
</body>
</html>Recommended: "htmlknowledge"
The above is the detailed content of How to determine whether the content of the text box in html is empty. For more information, please follow other related articles on the PHP Chinese website!
Statement：
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Previous article：What is the difference between xml and htmlNext article：What is the difference between xml and html