Javascript: split string into 2d array

Question

I have a string of month and years:

var months= "2010_1,2010_3,2011_4,2011_7";

I want to make this into a 2d array with the year in the first position of each array and the month in the second position. In other words, I want to end up with this:

var monthArray2d = [[2010,1],[2010,3][2011,4],[2011,7]];

The way I do this currently is:

//array of selected months
var monthArray = months.split(",");

//split each selected month into [year, month] array
var monthArray2d = new Array();
for (var i = 0; i < monthArray.length; i++) {
    monthArray2d[i] = monthArray[i].split("_");

Is there a way to condense that code so that I never need to use the monthArray var?

Answer 1

You can use replace to get more compact code:

var months= "2010_1,2010_3,2011_4,2011_7";
var monthArray2d = []

months.replace(/(\d+)_(\d+)/g, function($0, $1, $2) {
    monthArray2d.push([parseInt($1), parseInt($2)]);
})

or map if your target browser supports it:

monthArray2d = months.split(",").map(function(e) {
    return e.split("_").map(Number);
})

Basically, the first function looks for year/month patterns "digits underscore digits", and stores each found substring in an array. Of course, you can use other delimiters instead of underscore. The function doesn't care about the values' delimiter (comma), so that it can be whatever. Example:

var months= "2010/1 ... 2010/3 ... 2011/4";
months.replace(/(\d+)\/(\d+)/g, function($0, $1, $2) {
    monthArray2d.push([parseInt($1), parseInt($2)]);
})