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JavaScript

Posted by Mathew Gries
Mathew Gries
7,071 Points

Are the loop counter conditions backwards?

In the video example, you are iterating over the column count for the outer loop, and the row count for the inner loop. Should we not be iterating over the row count for the outer loop, since this loop should be representing each row on the board, and then iterating over the column count in the inner loop, since this should be representing each column in the row?

Maybe this was corrected in a future video, so we will see.

Your code

createSpaces(){
        const spaces = [];

        for(let x = 0; x < this.columns; x++){
            const columns = [];

            for(let y = 0; y < this.rows; y++){
                const space = new Space(x,y);
                columns.push(space);
            }

            spaces.push(columns);
        }
        return spaces;
    }

What I believe this should be

    createSpaces(){
        const spaces = [];

        for(let x = 0; x < this.rows; x++){
            const row = [];

            for(let y = 0; y < this.columns; y++){
                const space = new Space(x,y);
                row.push(space);
            }

            spaces.push(row);
        }
        return spaces;
    }

1 Answer

Steven Parker
Steven Parker
229,783 Points
Steven Parker
Steven Parker
229,783 Points

I don't think it matters if you loop row-first or column-first; but my personal preference is also rows on the outer loop. However, it does matter that you keep "x" and "y" correctly associated with columns and rows respectively:

        for (let y = 0; y < this.rows; y++) {         // y for rows
            const row = [];
            for (let x = 0; x < this.columns; x++) {  // x for columns
                const space = new Space(x, y);        // note: columns come first!
                // ...
Mathew Gries
Mathew Gries
7,071 Points

not sure that part matters as much. It matters more where they get placed in the Space() constructor. I also think of 2D arrays as rows as the first array index, and columns as the indexes in the rows. This just seemed backwards to me. Maybe it'll play out in the end and make sense why it was it was done this way

Steven Parker
Steven Parker
229,783 Points
Steven Parker
Steven Parker
229,783 Points

The order in creating the "space" was my point. In your 2nd example, it should be "new Space(y, x)".