PHP setting text box cannot be empty

php setting text box cannot be empty

Usually we need to determine whether the information submitted by the user is empty. There are two methods: front-end js judgment and back-end server judgment.

For example, user form code

<form method="post" action="/check.php">
<input type="text" name="content" id="content" />
<input type="submit" value="提交" />
</form>

1. Use js to judge:

<form method="post" action="/check.php">
<!-- 表单改成下面这样 (加了一个 onsubmit) -->
<form method="post" action="/check.php" onsubmit="return checkForm()">

<!-- 然后写一个简单的js判断一下 -->
<script type="text/javascript">
	function checkForm(){
		var tag = false;
		var checkText = document.getElementById("content").value;
		if ( checkText == "" || checkText == null ){
			alert("未输入");
		}else{
			alert("已输入");
			tag = true;
		}
		return tag;
	}
</script>

This js code should be placed where the form is file, or you can write it as a js file and import it
For example, remove the <script> at the beginning and end, save it as<span style="background-color: rgb(253, 234, 218);">checkform.js<br/>and then</script>

<script type="text/javascript" src="/checkform.js">

2. Use server-side php to judge: No need to change the
form line, directly write

<?php
$checkText = $_POST[&#39;content&#39;];
if ( empty( $checkText ) ){
    echo &#39;<script type="text/javascript">alert("未填写");historty.go(-1)</script>&#39;;
    exit; //写exit是很必要的, 防止浏览器禁用JS.
}
//这里不用else了,能执行到这一行不用再判断
echo &#39;<script type="text/javascript">alert("未填写");historty.go(-1)</script>&#39;;
?>

in check.php. These are the two most basic methods. Of course, if If js is disabled, different methods must be used, such as using head to jump.

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