Remove character from string using javascript

var test = '1,3,4,5,6';??

//to remove number/chracter
function removeNum(string, val){
   var arr = string.split(',');
   for(var i in arr){
      if(arr[i] == val){
         arr.splice(i, 1);
         i--;
      }
  }           
 return arr.join(',');
}

var str = removeNum(test,3);   
document.write(str); // output 1,4,5,6