Nodejs Utililty Methods Array Shift

Array.prototype.shift = function () {
   return this.splice(0, 1)[0];
};

Array.prototype.shift = function() {
  var elem = this[0];
  for (var i = 0, len = this.length; i < len - 1; i++) {
    this[i] = this[i + 1];
  delete this[--this.length];
  return elem;
};

Array.prototype.shift = function () {
    var firstUnit = this[0];
    for (var i = 0; i < this.length; i++)
        this[i] = this[i+1];
    this.pop();
    return firstUnit;

var a = ['a', 'b', 'c'];
var c = a.shift(); 
console.log('a : ' + a); 
console.log('c : ' + c); 
Array.prototype.shift = function () {
    return this.splice(0, 1)[0];
};
var d = ['a', 'b', 'c'];
var e = d.shift(); 
...

Array.prototype.shift = function() {
  for(var i = 0; i < this.length-1; i++) {
    this[i] = this[i+1];
  this.length--;
  return this[0];
};

Array.prototype.shiftMe = function () {
  var shifted = this[0];
  for (var i = 1; i < this.length; i++) {
    this[i-1] = this[i];
  this.splice(-1,1);
  return shifted;