Setting an object to a split array

Question

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.

Answer 1

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 :)

Answer 2

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.

Answer 3

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.