Create Nested Empty Array Using For Loop Javascript

Question

I'm trying to make a nested array with parameters that accepts 2 numbers as arguments that will be used to create the dimensions of a board.

In the following code, I would expect a 5X5 nested array to be printed, but instead am getting a 5x15 nested array.

function NestedArray(x,y) {
    rows = [];
    cells = [];
    board = [];
    for (var i = 0; i < x; i++) {
        for (var j = i; j < y; j++) {
           rows.push(cells); 
        }
        board.push(rows);
    }
    console.log(board);
}

NestedArray(5,5);

Please forgive any formatting errors, I'm new to JS.

You need to create a new array for every row. Currently your board refers to the very same array 5 times. — Bergi
– Bergi, Commented Mar 2, 2016 at 17:34
See stackoverflow.com/questions/16512182/…, and many other similar questions. — user663031
– user663031, Commented Mar 2, 2016 at 18:15

madox2 · Accepted Answer · 2016-03-02 17:37:58Z

1

In the first loop you need to create row and push it to the board. In the second loop you need to create cell and push it to the current row:

function NestedArray(x,y) {
    board = [];
    for (var i = 0; i < x; i++) {
        var arr = []; // create row
        board.push(arr);
        for (var j = 0; j < y; j++) {
           arr.push([]); // create and push cell to row
        }
    }
    console.log(board);
}

NestedArray(5,5);

edited Mar 2, 2016 at 17:37

answered Mar 2, 2016 at 17:35

madox2

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1 Comment

Jessie Richardson Over a year ago

Thank you for your help!

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