Последовательное отображение содержимого папки средствами javascript

myPic=new Array("gallery/fig1.jpg","gallery/fig2.jpg",
"gallery/fig3.jpg","gallery/fig4.jpg","gallery/fig5.jpg","gallery/fig6.jpg",
"gallery/fig7.jpg","gallery/fig8.jpg","gallery/fig9.jpg","gallery/fig10.jpg",
"gallery/fig11.jpg","gallery/fig12.jpg","gallery/fig13.jpg","gallery/fig14.jpg",
"gallery/fig15.jpg","gallery/fig16.jpg","gallery/fig17.jpg","gallery/fig18.jpg")

thisPic=0
imgCt=18

function processPrevious(){ // заменяет картинки в перед в 6 ячейках      
 if(document.images&&thisPic>=6){
  thisPic=thisPic-6
  document.mP1.src=myPic[thisPic];
  document.mP2.src=myPic[thisPic+1]
  document.mP3.src=myPic[thisPic+2]
  document.mP4.src=myPic[thisPic+3]
  document.mP5.src=myPic[thisPic+4]
  document.mP6.src=myPic[thisPic+5]
 }
}
function processNext(){
 if(document.images&&thisPic<(imgCt-6)){
  thisPic=thisPic+6
  document.mP1.src=myPic[thisPic];
  document.mP2.src=myPic[thisPic+1]
  document.mP3.src=myPic[thisPic+2]
  document.mP4.src=myPic[thisPic+3]
  document.mP5.src=myPic[thisPic+4]
  document.mP6.src=myPic[thisPic+5]
 }
}