How do you split an array into array pairs in JavaScript?

Question

I want to split an array into pairs of arrays.

var arr = [2, 3, 4, 5, 6, 4, 3, 5, 5]

would be

var newarr = [
    [2, 3],
           


        

Answer 1

Here's a good generic solution:

function splitInto(array, size, inplace) {
    var output, i, group;

    if (inplace) {
        output = array;

        for (i = 0; i < array.length; i++) {
            group = array.splice(i, size);

            output.splice(i, 0, group);
        }
    } else {
        output = [];

        for (i = 0; i < array.length; i += size) {
            output.push(array.slice(i, size + i));
        }
    }

    return output;
}

For your case, you can call it like this:

var arr= [2,3,4,5,6,4,3,5,5];
var newarr = splitInto(arr, 2);

The inplace argument determines whether the operation is done in-place or not.

Here's a demo below:

function splitInto(array, size, inplace) {
    var output, i, group;

    if (inplace) {
        output = array;

        for (i = 0; i < array.length; i++) {
            group = array.splice(i, size);

            output.splice(i, 0, group);
        }
    } else {
        output = [];

        for (i = 0; i < array.length; i += size) {
            output.push(array.slice(i, size + i));
        }
    }

    return output;
}

var arr= [2,3,4,5,6,4,3,5,5];
var newarr = splitInto(arr, 2);

disp(newarr);

// or we can do it in-place...
splitInto(arr, 3, true);

disp(arr);

function disp(array) {  
  var json = JSON.stringify(array);

  var text = document.createTextNode(json);
  var pre = document.createElement('pre');

  pre.appendChild(text);
  document.body.appendChild(pre);
}