javascript array of arrays

Question

I have the following arrays:

var dates = new Array();
var answers = new Array();

Once Populated, they will be the same length. What I need is an array that pair the same index values of the arrays. Like so:

var pairedArray = new Array();
//pairedArray should have the form: [[dates[0], answers[0]], [dates[1], answers[1]], ...., [dates[n-1], answers[n-1]]]

e.g.

data: [
 [Date.UTC(2010, 0, 1), 29.9], 
 [Date.UTC(2010, 2, 1), 71.5], 
 [Date.UTC(2010, 3, 1), 106.4]
 ]

How is this possible given that I have two arrays of the same length, answers and dates that are already populated?

• Daniel A. White: i wouldn't do the inside as an array.
• hugomg: Just a minor nitpick - in general, [] notation is way more awesome than new Array()

Answer 1

If you know they are always the same length, simply loop through one and add both to the result:

var data = [];
for(var i=0; i<dates.length; i++){
 data.push([dates[i], answers[i]]);
}

Answer 2

var data = $.map(dates, function(v,i) { return [ [ v,answers[i] ] ]; });

---

You can use the jQuery.map()^[docs] method, but you need to double-wrap the returned Array because when $.map gets an Array, it performs a concat.

Answer 3

var firstArray = ...
var secondArray = ...
if (firstArray.length === secondArray.length) {
 var result = [];
 for (var i = 0; i < firstArray.length; i++) {
 result.push({ [ firstArray[i], secondArray[i] ] });
 }
 // TODO: do something with the result
}

• James Montagne: Don't think that will work with the {} unless you give the property a name {something: [...]}

Answer 4

Try this

var dates = new Array();
var answers = new Array();
var pairedArray = new Array();
$.each(dates, function(i){
 pairedArray.push([ dates[i], answers[i] ]);
});