function updateDomainPreview(inputId) {
	
	// Get the string
	var usernameString = document.getElementById(inputId).value;
	
	// Get the length of the string
	var usernameStringLength = usernameString.length;
	
	var domain = '';
	
	// Loop the string
	for(var i = 0; i < usernameStringLength; i++) {
		
		// Get the current character
		var character = usernameString.substr(i, 1);
		
		// If the character is not valid for a domain name
		if(!stringIsValidForDomain(character)) {
			
			// replace space with &nbsp;
			if(character == " ") {
				character = "&nbsp;&nbsp;";
			}
			
			// Style the character
			character = '<span>' + character + '</span>';
			
		}
		
		// Add the character to the string
		domain += character;
		
	}
	
	// Set string
	document.getElementById('domainPreviewUsername').innerHTML = domain;
	
}

/**
* Validate a character for use in domain
*/
function stringIsValidForDomain(string) {
	
	var okPattern = /^[a-z0-9]+$/;
	return okPattern.test(string);
	
}