Nodejs Utililty Methods Array Max Matrix

Array.prototype.matrix = function (rows, cols, initial) {
    var arr = [];
    for (var i = 0; i < rows; i++) {
        var columns = [];
        for (var j = 0; j < cols; j++) {
            columns[j] = initial;
        arr[i] = columns;
    return arr;
var matrix = [].matrix(3, 3, 10);
console.log(matrix);
arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
result = arr.reduceRight(function reduce(sum, value) {
    return "" + sum + value;
});
console.log(result);

Array.prototype.max2d = function ( si, ei, sj, ej, calc_maxm, update_array ) {
  var maxm = 0.0;
  for ( var ip = si; ip <= ei; ip++ ) {
    for ( iq = sj; iq <= ej; iq++ ) {
      if ( calc_maxm ) {
        this[ip][iq] = calc_maxm.call(this,this[ip][iq]);
      if ( this[ip][iq] > maxm ) {
        maxm = this[ip][iq];
...

Array.prototype.maxChildren = function(childrenPos) {
  if (childrenPos.length == 1) {
    return childrenPos[0];
  if (this[childrenPos[0]] >= this[childrenPos[1]]) {
    return childrenPos[0];
  } else {
    return childrenPos[1];