html = '<td><input type="number" name="limit_num[]" class="limit_num" value="" class="rate-cl" min="0"  οnkeyup="return changeVal(this)"></td>';
          
function changeVal(obj){
   var val = obj.value;
   console.log(val);
   obj.value = val.replace(/^(0+)|[^\d]+/g,'')
}