Handling Edge and Corners - getNeighbourhoodCells

gameOfLife.js corners and edges

// Will handle all Corners, Edges and Other Cells in Grid to find the neighbours of the the current examined cell
getNeighbourhoodCells(col, row, lastColumn, lastRow) {
    const indexStart = -1, indexEnd = 2;

    // TOP LEFT CORNER - 3 neighbours
    if (col === 0 && row === 0) {
        return {
            xStart: col,
            xEnd: indexEnd, // 2
            yStart: row,
            yEnd: indexEnd // 2
        }
    }
    // BOTTOM LEFT CORNER - 3 neighbours
    else if (col === 0 && row === lastRow) {
        return {
            xStart : col, // 0
            xEnd : indexEnd, // 2
            yStart : indexStart, // -1
            yEnd : indexEnd + indexStart // 1
        }
    }
    // TOP RIGHT CORNER - 3 neighbours
    else if (row === 0 && col === lastColumn) {
        return {
            xStart : indexStart, // -1;
            xEnd : indexEnd + indexStart, // 1
            yStart : row, // 0,
            yEnd : indexEnd, // 2
        }
    }
    // BOTTOM RIGHT CORNER - 3 neighbours
    else if (col === lastColumn && row === lastRow) {
        return {
            xStart: indexStart, // -1;
            xEnd: indexEnd + indexStart, // 1
            yStart: indexStart,//  -1;
            yEnd: indexEnd + indexStart // 1
        }
    }
    // TOP ROW EDGE - 5 neighbours
    else if (row === 0 && col > 0 && col < lastColumn) {
        return {
            xStart: indexStart, // -1,
            xEnd :indexEnd, // 2,
            yStart : row, // 0,
            yEnd : indexEnd // 2
        }
    }
    // BOTTOM ROW EDGE - 5 neighbours
    else if (row === lastRow && col > 0 && col < lastColumn) {
        return {
            xStart: indexStart, // -1,
            xEnd: indexEnd, // 2,
            yStart: indexStart, // -1,
            yEnd: indexEnd + indexStart // 1,
        }
    }
    // RIGHT COLUMN EDGE - 5 neighbours
    else if (col === lastColumn && row > 0 && row < lastRow) {
        return {
            xStart : indexStart, // -1,
            xEnd : indexEnd + indexStart, // 1,
            yStart : indexStart, // -1,
            yEnd : indexEnd // 2,
        }
    }
    // LEFT COLUMN EDGE - 5 neighbours
    else if (col === 0 && row > 0 && row < lastRow) {
        return {
            xStart : col, // 0,
            xEnd : indexEnd,// 2,
            yStart : indexStart, // -1,
            yEnd : indexEnd //2,
        }
    }
    // ALL OTHERS CELLS - 8 neighbours
    else {
        return {
            xStart : indexStart, // -1,
            xEnd : indexEnd, // 2,
            yStart :indexStart, //  -1,
            yEnd : indexEnd // 2,
        }
    }
}