get two Elements by Id in same js function [duplicate]

My question is: Is that possible to add the same element without rewriting the same variable. I am creating a slider, and i need to append a div with a class slide-el into block slider. Here is a part of code

    var body, html, sliderBody, btnLeft, btnRight, i, parts, vHeight, vWidth;
//Variable definitions
var i = 0,
    parts = 3,

    //Main html elements
    body = document.body,
    html = document.element,

    //viewport Height and Width
    vHeight = window.innerHeight,
    vWidth = window.innerWidth,

    sliderBody = _id("slider"),
    btnLeft = _id("btn-left"),
    btnRight = _id("btn-right"),

    urls = ["http://www.wallpapereast.com/static/images/pier_1080.jpg",
            "http://www.wallpapereast.com/static/images/pier_1080.jpg",
            "http://www.wallpapereast.com/static/images/pier_1080.jpg",
            "http://www.wallpapereast.com/static/images/pier_1080.jpg"];

    slide = _createEl("div");
    slide.className += "slide-el";

function _id(el){
  return document.getElementById(""+ el +"");
}
function _createEl(el){
  return document.createElement(""+ el +"");
}
window.onload = function(){
  slideLayout();
}

function slideLayout(){
  for(var i=0; i < urls.length; i++){
    sliderBody.appendChild(slide);
  }
}

The problem is that I can't append the same element that many times. It just creates one element instead of 4.

For you to understand better I made a fiddle:

https://jsfiddle.net/ud7dvn3z/

appendChild will remove the node from wherever it is before appending it to its new location, so you need to make copies of the node instead. You can use cloneNode for that. The true makes cloneNode perform a deep clone, i.e. with all its child nodes.

for(var i = 0; i < urls.length; i++){
  sliderBody.appendChild(slide.cloneNode(true));
}

Okey guys! I found an answer. I have to put

slide = _createEl("div");
slide.className += "slide-el";

into for loop. Now it looks like this:

for(var i=0; i < urls.length; i++){
  slide = _createEl("div");
  slide.className += "slide-el";
  sliderBody.appendChild(slide);
}