Extracting the most duplicate value from an array in JavaScript (with jQuery)

Question

I have several array to deal with. I need to extract the most duplicate value from each array.

From [3, 7, 7, 7], I need to find the value 7

Answer 1

Array.prototype.mostFreq=function(){
 var what, a= this.concat(), ax, freq,
 count, max=0, limit= a.length/2;
 while(a.length){
  what= a.shift();
  count=1; 
  while((ax= a.indexOf(what))!= -1){
   a.splice(ax,1); // remove counted items  
   ++count;
  }
  // if any item has more than half the array, quit counting
  if(count> limit) return what; 
  if(count> max){
   freq= what;
   max= count;
  }
 }
 return freq;
}
var a=[1,1,2,5,4,2,7,7,1,1,1,3,7,7,3,4,3,7,3,5,6,2,3,1,1,7,7,2,4,3,6,7,6,6]
alert(a.mostFreq())