How can I use jquery to parse out parameters from an encoded url with custom separators and place them into a string with pre-defined positions?

JJ2357
JJ2357 used Ask the Experts™
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My goal is to extract values from name-value pairs within a URL and return those values into a string that can be inserted into a web tracking tag.  Th using a js function. The string has fifteen positions separated by "-_-".  No matter where each name-value pair appears within the URL, values most always be inserted into the same position within the tracking tag string.  For example, the value(s) for the name apple must always appear in the first position, the value(s) for the name banana must always appear in the second position, and the value(s) for the name watermelon must always appear in the fifth position.

The URL will have a pound sign followed by an indefinite number of name-value pairs (up to 15). The name value pairs, connectors, and separators are encoded.  Values are strings that may be joined by "+" symbol.  Finally, Names may appear multiple times within the URL, each time with a different value.  However, since names only exactly one corresponding spot within the tracking tag string, the associated values must be joined into the same position (using "+").

Example URL:
http:www.mysite.com#currentPage=1&c%5B%5D=e%3A1119//e+apple//%3Aeq//red&c%5B%5D=e%3A1119//e+banana//%3Aeq//yellow+black&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//red&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//black

Example function using the tracking tag string created from above:
cmCreateElementTag("Tracking Parent", "Tracking Child","red-_-yellow+black-_--_--_-red+black-_--_--_--_--_--_--_--_--_--_-");

I'd like to use jquery to extract the values from the URL and place them in the right position within the tracking tag string.
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RobOwner (Aidellio)
Most Valuable Expert 2015

Commented:
http://jsbin.com/bevivehaka/1/edit?js,console#J:L1

var myindex = {
	apple: 1,
	banana: 2,
	watermelon: 5
};
var myurl = "http://www.mysite.com#currentPage=1&c%5B%5D=e%3A1119//e+apple//%3Aeq//red&c%5B%5D=e%3A1119//e+banana//%3Aeq//yellow+black&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//red&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//black";

$(function() {
	var querystring = myurl.substring(myurl.indexOf('#')+1);
	var vars = decodeURIComponent(querystring).split('&');
	var results = {};
    for (var i = 1; i < vars.length; i++) {
        var pair = vars[i].split('=');
		var vals = pair[1].split('//');
		var fruit = vals[1].substring(2);
		var color = vals[3];
		if (results[fruit] === undefined) {
			results[fruit] = color;
		}
		else {
		  results[fruit] += "+" + color;
		}
    }
	console.dir(results);
	var tracking = Array.apply(null, new Array(15)).map(String.prototype.valueOf,"");
	$.each(results, function(i, el) {
		tracking[myindex[i]] = el;
	});
	console.log('cmCreateElementTag("Tracking Parent", "Tracking Child",'+tracking.join("-_-")+')');
});

function parseQueryString(query) {
    var vars = query.split('&');
    for (var i = 0; i < vars.length; i++) {
        var pair = vars[i].split('=');
        if (decodeURIComponent(pair[0]) == variable) {
            return decodeURIComponent(pair[1]);
        }
    }
    console.log('Query variable %s not found', variable);
}

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Author

Commented:
Thanks, Rob.  Works great, with the exception of prepending "-_-" to the beginning of the string and not including double quotes around the string.  
Result:
 -_-red-_-yellow+black-_--_--_-red+black-_--_--_--_--_--_--_--_--_-

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Expected result:
"red-_-yellow+black-_--_--_-red+black-_--_--_--_--_--_--_--_--_-"

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Additionally, in the event that the URL contains an unencoded name-value pair, the function fails.  For example, if you append &name=value to the end, an undefined error is returned.
RobOwner (Aidellio)
Most Valuable Expert 2015

Commented:
Ok i've updated the code as the index was out by 1 (zero based array - first element is at index 0) http://jsbin.com/xukaso/1/edit?js,console#J:L1

As for the additional variables in the querystring, given that they weren't in your original spec, I haven't accounted for them.  So What are the variables that need to be parsed?  Will they always be the c[] variable or ?
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Owner (Aidellio)
Most Valuable Expert 2015
Commented:
I've modified it so that all other variables are parsed into "otherVars" object whilst the array variables are parsed into the required string (http://jsbin.com/xukaso/1/edit?js,console)

var myindex = {
	apple: 0,
	banana: 1,
	watermelon: 4
};
var myurl = "http://www.mysite.com#currentPage=1&c%5B%5D=e%3A1119//e+apple//%3Aeq//red&c%5B%5D=e%3A1119//e+banana//%3Aeq//yellow+black&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//red&c%5B%5D=e%3A1119//e+watermelon//%3Aeq//black&othervar=12345";

$(function() {
	var querystring = myurl.substring(myurl.indexOf('#')+1);
	var vars = decodeURIComponent(querystring).split('&');
	var results = {};
	var otherVars = {};
	// loop through the variables found
	for (var i = 0; i < vars.length; i++) {
		// find each pair of name/values
		var pair = vars[i].split('=');
		// we only want the "array" variables
		if (pair[0].indexOf('[]') > 0) {
			// each value is separated by //
			var vals = pair[1].split('//');
			// fruit and color found as below
			var fruit = vals[1].substring(2);
			var color = vals[3];
			// initialise the object with the color
			if (results[fruit] === undefined) {
				results[fruit] = color;
			}
			else {
				// If the fruit has already been found, add the corresponding color to the already existing value
				results[fruit] += "+" + color;
			}
		}
		else {
			// record all the other querystring variables here
			otherVars[pair[0]] = pair[1];
		}
	}
	// output the results
	console.dir(results);
	// output the other variables
	console.dir(otherVars);

	// now the cmCreateElementTag
	// create an array of 15 empty string values
	var tracking = Array.apply(null, new Array(15)).map(String.prototype.valueOf,"");
	// loop through this new array and assign the corresponding index retrieved from the myindex object
	$.each(results, function(i, el) {
		tracking[myindex[i]] = el;
	});
	// join the array as a string, serarated by -_- and output in the corresponding format
	console.log('cmCreateElementTag("Tracking Parent", "Tracking Child",'+tracking.join("-_-")+')');
});

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Author

Commented:
works like a charm, tx.
RobOwner (Aidellio)
Most Valuable Expert 2015

Commented:
not a problem.  Sounds like that's solved it for you.  If so, go ahead and close the question: http://support.experts-exchange.com/customer/portal/articles/608621

Author

Commented:
Sorry for not being clear in the original.  Thanks for the extra work.

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