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
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