Constant-time helper function to get a particular value from a cookie with in the broswer

getCookieValue.js

    function getCookieValue(key) {
    	var namePosition,
    		nameValuePair,
    		value;
    	
    	//step 0: append an equal sign to the key we are looking for
    	key = key + '=';
    	
    	//step #1: find the position of the particular key we want with in the cookie string of the 
    	namePosition = document.cookie.indexOf(key);
    	
    	//no value with that name in the cookie
    	if (namePosition === -1) {
    		return '';
    	}
    	
    	//step #2: now that we know where they key is located, we can eliminate the parts of the cookie string we are sure we do not care about.
    	//(aka: everything BEFORE the key)
    	//This will put the the key we are looking for at the very beginning of the string 
    	nameValuePair = document.cookie.substring(namePosition);
    	
    	//step #3: split the remaining cookie string in to an array of key-value strings.
    	//Because of step #2, we are certain that the first element in the string is is key-value string we want
    	nameValuePair = nameValuePair.split(';')[0];
    	
    	//step#4 (final step): extract the value from the key-value string
    	value = nameValuePair.split('=')[1];
    	
    	return value;
    	
    }