Diagonal Attack

(arr) => {
    const split = (string, ch) => {
        let array = [], item = '';
        const len = string.length;
        for(let i = 0; i < len; i++) {
            if(string[i] !== ch) {
                item += string[i];
            } else {
                array[array.length] = item;
                item = '';
            }
        }
        array[array.length] = item;
        return array;
    };

    let matrix = [], len = arr.length;
    for(let i=0; i<len; i++) {
        let row = split(arr[i], ' ');
        for(let j = 0; j < row.length; j++) {
            row[j] = Number(row[j]);
        }
        matrix[i] = row;
    }

    let sumMain = 0, sumSecond = 0;
    for(let i=0; i<len; i++) {
        for(let j=0; j<len; j++) {
            if(i === j) sumMain += matrix[i][j];
            if(i+j === len-1) sumSecond += matrix[i][j];
        }
    }

    if(sumMain === sumSecond) {
        for(let i=0; i<len; i++) {
            for(let j=0; j<len; j++) {
                if(i === j || i + j === len-1) continue;
                matrix[i][j] = sumMain;
            }
        }
    }

    let output = '';

    for(let row = 0; row < matrix.length; row++) {
        for(let col = 0; col < matrix[row].length; col++) {
            output += `${matrix[row][col]} `;
        }
        output += '\n';
    }

    console.log(output);
}