Nodejs Utililty Methods Array Concatenate

Array.prototype.concat = function(){
  var result = [];
  this.forEach(function(subArray){
    result.push.apply(result, subArray);
  });
  return result;
var a = [[2,3,4,5],[11,2,333],[33,232,21]];
a.concat();
...

Array.prototype.concat = function(ar) {
  var results = new Array(this.length + ar.length);
  for (var i = 0, len = this.length; i < len; i++) {
    results[i] = this[i];
  for (var i = 0, len = ar.length; i < len; i++) {
    results[len + i] = ar[i];
  return results;
...

var my_array=Array.prototype.concat;
Array.prototype.concat=function (arg) {
    var result = arg[0];
    for (var i = 1; i < arg.length; i++) {
        result += "-" + arg[i];
    console.log(result);
var piyo=new Array(100,200,300);
...

Array.prototype.concatAll = function() {
  var results = [];
  this.forEach(function(subArray) {
    results.push.apply(results, subArray);
  });
  return results;
};

Array.prototype.concatAll = function() {
  var results = [];
  this.forEach(function(subArray) {
    subArray.forEach(function(item) {
      results.concat(item);
    });
  });
  return results;

Array.prototype.concatAll = function() {
  var results = [];
  this.forEach(function(subArray) {
    subArray.forEach(function(innerData){return results.push(innerData)})
  });
  return results;
};

Array.prototype.concatAll = function() {
  var results = [];
  this.forEach(function(subArray) {
    subArray.forEach(function(element) {
      results.push(element);
    });
  });
  return results;
};
...

Array.prototype.concatAll = function() {
    let result = [];
    this.forEach(items => 
        result = result.concat(items)
    );
    return result;

Array.prototype.concatAll = function() {
  let results = [];
    for (let i = 0; i < this.length; i++) {
        results.push.apply(results, this[i]);
  return results;
};

Array.prototype.concatAll = function() {
  return this.reduce((results, current) => {
    if(Array.isArray(current)) {
        return results.concat(current).concatAll();
    } else {
        return (results.push(current), results);
  }, []);
};
...