PHP setting text box cannot be empty-PHP Problem-php.cn

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>

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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>

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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