Elegant way to convert string of Array of Arrays into a Javascript array of arrays?

Question

I have an ajax request that returns a list of values like this:

"[-5, 5, 5], [-6, 15, 15], [7, 13, 12]"

I need it to be a javascript array with numbers:

[[-5, 5, 5], [-6, 15, 15], [7, 13, 12]]

I tried to replace the '[' and ']' for a '|' and then split by '|' and foreach item split by ',' and add them to an array, but this is not elegant at all.

Do you guys have any suggestions?

• Sterling Archer: Define elegant? Most string manipulations aren't really pretty.
• RobG: Using split + for loop where perhaps match would do is likely not elegant or pretty. ;-)

Answer 1

You can use JSON.parse() to convert that string into an array, as long as you wrap it in some brackets manually first:

var value = "[-5, 5, 5], [-6, 15, 15], [7, 13, 12]";
var json = JSON.parse("[" + value + "]");
console.log(json);

I would suggest correcting the output at the server if possible, though.

• cesarferreira: Thanks for the fast & elegant response!
• Suhail Mumtaz Awan: that is pretty, :)
• Kishan Mehta: This does not accept string like this "[Name, 26], [Name2, 45]" Any idea how to do it?
• Marty: @Kishan Depends greatly on the context and what can appear in place of Name - probably in this case you just want to do something like create a 2D array by extracting all the contents of [ ] pairs and then exploding on commas.
• Kishan Mehta: Yes, name can be a string value which is giving me an error with JSON.parse. I am using eval as last resort but I heard that eval is not a good choice?

Answer 2

This solution is stupid in practice -- absolutely use JSON.parse as others have said -- but in the interest of having fun with regular expressions, here you go:

function getMatches(regexp, string) {
 var match, matches = [];
 while ((match = regexp.exec(string)) !== null)
 matches.push(match[0]);
 return matches;
}
function parseIntArrays(string) {
 return getMatches(/\[[^\]]+\]/g, string)
 .map(function (string) {
 return getMatches(/\-?\d+/g, string)
 .map(function (string) { 
 return parseInt(string); 
 });
 });
}
parseIntArrays("[-5, 5, 5], [-6, 15, 15], [7, 13, 12]");

Answer 3

If you're generating the data, and you trust it, just use eval:

var string = "[-5, 5, 5], [-6, 15, 15], [7, 13, 12]"
var arrays = eval('[' + string + ']');

Alternatively, start returning well-formed JSON.

• user229044: In before 'eval is evil'.
• user229044: @upvoter There's really no good reason to use eval when the string is also valid JSON, please downvote me instead.

Answer 4

In a function

var strToArr = function(string){ return JSON.parse('[' + string + ']')}
console.log(strToArr("[-5, 5, 5], [-6, 15, 15], [7, 13, 12]"));

• Marty: Shouldn't that function be named stringToArr?
• Marty: @Jashwant Don't look at me.

Answer 5

var string = "[-5, 5, 5], [-6, 15, 15], [7, 13, 12]";
var arr = [];
var tmp = string.split('], ');
for (var i=0; i<tmp.length; i++) {
 arr.push(tmp[i].replace(/\[|\]/g, '').split(', '));
}

Typing on my iPad so I apologize in advance for any typos.