Convert string of array, with array of array(s)

Question

I have a string like this: var data = "[[1, 2, 3,], [3, 2, 1]]"; I am using the well known blossom function, which expects (as input) an array of this type: [[1, 2, 3,], [3, 2, 1]], [...], [...]]

As you can see, I am trying to provide this with my: data variable, but this is currently a string, so I need to convert it to the right type. I know that I can convert a string to an array like this:

var input = "1, 2, 3";
var array = input.split(",");

Then the result of the above will be: ["1", "2", "3"]

But I need to be able to give input like this: var data = "[[1, 2, 3,], [3, 2, 1]]"; And expect this output: [[1, 2, 3,], [3, 2, 1]]; Also, notice that the values in the brackets are numbers and not string.

I also tried doing this:

var data = "[1, 2, 3,], [3, 2, 1]"; var res = data.split(",");

This gives the output: ["[1", " 2", " 3", "]", " [3", " 2", " 1]"]

Finally I also found this example: Convert string with commas to array where the solution made use of JSON.parse(...), but I did not make this work either.

• Denys Séguret: Is the trailing comma in the first array a typo ? If not it will make it harder to use JSON.parse. If it is then just go for it.
• MOR_SNOW: No, the commas are not a type :)
• user1106925: If you control and trust the source of the data, you can use Function constructor as a substitute for eval. It evaluates the code just like any other script, hence the trust caveat, but by using Function it at least gets eval'd as though the function was created in the global scope, and it avoids performance problems. var array = new Function("return " + data)();

Answer 1

If your array have trailing commas you can use this code:

var data = "[[1, 2, 3,], [3, 2, 1]]";
var array = JSON.parse(data.replace(/,\s*]/g, ']'));
console.log(array);

and if you have string like this:

var data = "[1, 2, 3,], [3, 2, 1]";

use

var array = JSON.parse('[' + data.replace(/,\s*]/g, ']') + ']');

Example:

var data = "[1, 2, 3,], [3, 2, 1]";
var array = JSON.parse('[' + data.replace(/,\s*]/g, ']') + ']');
console.log(array);

• MOR_SNOW: This give the output: "1,2,3,3,2,1". It's as if it ignores the brackets?
• T.J. Crowder: @MOR_SNOW: No, it doesn't. It gives you an array. Apparently the way you're outputting that array makes it look like that.
• MOR_SNOW: I need it to output this: "[[1,2,3,3,2,1]]". I could add those manually of course, but maybe you know a smarter way to it, in addition to the code you provided?
• user1106925: @MOR_SNOW: That isn't the output you show in the question.
• MOR_SNOW: Never mind, it's correct as you provided already. I missed something. Thanks man

Answer 2

As I said in comment, this isn't JSON, as there are trailing commas.

Modifying a string which isn't in JSON to make it possible to use JSON.parse looks like a silly hack, especially when a proper parsing is easy.

An alternative would be:

var arr = str.split(/[\[\]]+,?\s*/)
 .filter(Boolean)
 .map(s=>s.split(/\D+/).filter(Boolean).map(Number));

• T.J. Crowder: That adds a 0 to the end of the first array.
• Denys Séguret: @T.J.Crowder Thanks, fixed