[a_l]

var array = [[1,2,3,1,1,1,1,2,4],[4,2,1,1,1,1,3,4,4]],
    searchIndex = function(arr) {
      for(var i=0,arrIndex=0,maxIndex=0,startIndex=0,endIndex=0,l=arr.length; i<l; i++){
        if(arr[i]===arr[i+1]) {
          arrIndex++;   
        } else {
          if(arrIndex > maxIndex) {
            maxIndex = arrIndex;
            endIndex = i;
          }
          arrIndex = 0;
        }    
      }
      startIndex = endIndex - maxIndex;
      return [startIndex, endIndex];
    }
console.log(searchIndex(array[0]));
console.log(searchIndex(array[1]));