Demo - javascript-allow-alphanumeric-space

Edit This Code :
<html>
<body>
 
<input onkeypress="return Validate(event);" type="text" /><br/>
 <span style="color:red;" id="lblErrorMsg"></span>
<script>
 function Validate(e) {
	var keyCode = e.keyCode || e.which;
	var errorMsg = document.getElementById("lblErrorMsg");
	errorMsg.innerHTML = "";

	//Regex to allow only Alphabets Numbers Dash Underscore and Space
	var pattern = /^[a-z\d\-_\s]+$/i;

	//Validating the textBox value against our regex pattern.
	var isValid = pattern.test(String.fromCharCode(keyCode));
	if (!isValid) {
		errorMsg.innerHTML = "Invalid Attempt, only alphanumeric, dash , underscore and space are allowed.";
	}

	return isValid;
}

</script>
</body>
</html>
Result :