Copy code code as follows:
<script language = "javascript" type = "text/javascript">
Function Check (EVENT) {
// Every time the user presses the key, he will judge whether it is a number
if (event.keycode <48 || Event.keycode> 57) {{) {{) {{
Window.alert ("You are not entering the number!");
Return false;
}
}
</script>
<body>
<input type = "text" onKeypress = "Return Check (EVENT)"/>
</body>