Nodejs Utililty Methods Class Extend

Object.extend = function(destination, source) {
  for (var property in source) {
    if (source.hasOwnProperty(property)) {
      destination[property] = source[property];
  return destination;

Object.prototype.extend = function(obj) {
   for (var i in obj) {
      if (obj.hasOwnProperty(i)) {
         this[i] = obj[i];
};
Array.prototype.first = function() {
    return this.length && this[0];
...

Object.prototype.extend = function (object)
  var combined = this;
  object.each( function (value, key)
    combined[key] = value;
  });
  return combined;
};
...

Object.prototype.extend = function(other)
  let property;
  for (property in other)
    if( other.hasOwnProperty(property) &&
        other[property] != null )
      this[property] = other[property];
...

Object.extend = function(target) {
    Array.toArray(arguments, 1).forEach(function(source) {
        var fld;
        for (fld in source) {
            if (source.hasOwnProperty(fld)) {
                target[fld] = source[fld];
    });
...