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I'm not a javascript guru. I've got the following code below:

var aCookieValues = sCookieContentString.split('&'); // split out each set of key/value pairs
var aCookieNameValuePairs = aCookieValues.split('='); // return an array of each key/value

What I'm trying to do is split the first string via & and then create another array that takes the first array and splits it further via the = character that exists in every value in the aCookieValues array

I get the error aCookieValues.split is not a function.

I've seen an example that basically does the same thing but the second time this guy is using a loop:

(http://seattlesoftware.wordpress.com/2008/01/16/javascript-query-string/)

    // '&' seperates key/value pairs
    var pairs = querystring.split("&");

    // Load the key/values of the return collection  
    for (var i = 0; i < pairs.length; i++) {
        var keyValuePair = pairs[i].split("=");
        queryStringDictionary[keyValuePair[0]] = keyValuePair[1];
    }

Ultimately what I'm trying to achieve here is a final dictionary with key/value pairs based off the '=' split. I'm simply trying to split up a cookie's values and shove it into a nice dictionary so I can then get certain values out of that dictionary later on.

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    Why don’t you use the algorithm you already have? Commented Jul 15, 2010 at 2:11
  • what algorithm. You talking about the 2nd example? that's from that guy's blog. And honestly I don't fully understand a couple things he's doing such as = {}; and how he's creating a dictionary in JavaScript..there aren't dictionaries in JavaScript are there? Commented Jul 15, 2010 at 2:22
  • @coffeeaddict: Everything is a dictionary in JavaScript :) Commented Jul 15, 2010 at 2:23
  • ... See the "Objects" section here: crockford.com/javascript/survey.html Commented Jul 15, 2010 at 2:25
  • So you’re rather asking for an explanation of that code? Commented Jul 15, 2010 at 2:32

3 Answers 3

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You are getting this error because aCookieValues is an array, and it does not have a split method. You would need to call the split method on each element of aCookieValues:

var aCookieValues = sCookieContentString.split('&');

for (var i = 0; i < aCookieValues.length; i++) {
   var aCookieNameValuePairs = aCookieValues[i].split('=');

   // Handle aCookieNameValuePairs[0] as the key
   // Handle aCookieNameValuePairs[1] as the value
}

To shove everything in your nice dictionary, simply declare it before the for loop: var myDict = {}, and then put the following after the split('=') call:

myDict[aCookieNameValuePairs[0]] = aCookieNameValuePairs[1];

EDIT: Which, after reading your question properly, is the same method used in the code snippet you supplied. I hope at least this explains how that works :)

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15 Comments

I'm just wondering how not to do this with a loop the second time.
this is the line I don't get. myDict[aCookieNameValuePairs[0]] = aCookieNameValuePairs[1]; And I did not know there are JavaScript dictionaries after trying to look it up...there isn't looks like but I just found a nice article finally 4guysfromrolla.com/webtech/100800-1.shtml
You have to use a loop. Actually you could use map(), but that's quite advanced, and is just a shorthand for looping through all the elements of the array. (And it does not work in all browsers).
@coffeeaddict: JavaScript dictionaries are really straightforward. Your declare one: var myDict = {};... Then you simply do myDict['myKey'] = 'someValue';... You can then call alert(myDict['myKey']) and you'd be alerted someValue... That part you quoted is basically doing the same thing, since aCookieNameValuePairs[0] is just a string with the key of each element of aCookieValues, and aCookieNameValuePairs[1] is the value.
@coffeeaddict: I suggest checking out the section "Objects" at: crockford.com/javascript/survey.html... Note that ` = new Object()` and ` = {}` are the same thing. The latter is just a shorthand notation, called the "object literal".
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In your second line you are attempting to call split() on an array, when it is a function defined on strings.

Example:

"a=1&b=2&c=3".split('&') returns an array ['a=1','b=2','c=3']

Your code would then call split on the array:

['a=1','b=2','c=3'].split('=')

But that function doesn't exist. It seems like your goal is to split each string in the array, so the example you gave in the question seems appropriate - loop through each element and split it.

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split operates on a string. You're trying to split aCookieValues, which is an array. The example you cite is looping through the array, and then splitting each element as a string.

Just for fun, one way to deal with this would be to use a map function, which performs an action on each element of an array, and emits an array as a result. If you make a generic map function available to all your arrays, like this:

if (!Array.prototype.map) { // don't step on anyone's toes
  Array.prototype.map = function( f ) {
    var result = [];
    var aLen = this.length;
    for( x = 0 ; x < aLen ; x++ ) {
      result.push( f(this[x]) );
    }
    return result; 
  };
};

...you can call it as a method on your array directly. Thus:

​yourstring = 'x=3&y=4&zed=blah&something=nothing';
dictionary = yourstring.split('&').map( function(a){ return a.split('='); } );

dictionary will now be a nice clean array of (arrays of) name/value pairs, like this:

[["x", "3"], ["y", "4"], ["zed", "blahblah"], ["something", "nothing"]]

If your use case becomes complex, an approach like this can be a nice abstraction. Of course, you can arrange these data in other structures if needed, either by playing with a function passed into map, or processing in a separate pass.

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5 Comments

thanks, I'm not that advanced in JS yet..did not know of maps.
I don't understand how the passed in function with the x param works..is that basically some kind of delegate?
The map function above is defined as taking argument f. In the body of map, we see that the f argument is a function, which is called inside the for loop -- f(this[x]). The argument passed in is this[x] -- meaning, the current element of the original array in question. Think of the function(a) code (I changed it to a for clarity) as a sort of template -- a general form of the function we want to pass to map. When the function is actually applied inside map, we're just saying "take the actual argument, and slot it in wherever we had a in that "template".
I don't think map() is (yet?) standard. You can't rely on its presence or uniform behavior across implementations of js. I'm defining a basic version here, but it would probably be smart to check for it first. I'll add that to the answer.
cool I will definitely look into that moving forward as a valuable approach. I need to digest it first.

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