SOURCE

var button = document.getElementsByTagName('button')[0];
var input  = document.getElementsByTagName('input')[0];
var span = document.getElementsByTagName('span')[0];
button.addEventListener('click',()=>{
  dx2(input.value);
},false);


function dx1(value){
  if(!value){
    return;
  }
  var temp = [];
  for(var i = value.length - 1; i >= 0; i--){
    temp.push(value[i]);
  }
  if(temp[temp.length - 1] == '-'){
    temp.unshift(temp.pop());
  }
  span.textContent = temp.join('');
}

function dx2(value){
  var shang,ys,res=[],type;
  if(value[0] == '-'){
    shang = value.substr(1);
    type = '-'
  }else{
    shang = value;
  }
  do{
    ys = shang % 10;
    shang = parseInt(shang / 10);
    res.push(ys);
  }while(shang != 0);
  
  for(var i in res){
    if(res[i] == 0){
      res.shift()
    }else{
      break;
    }
  }
  res.unshift(type)
  span.textContent = res.join('');
}

<input type="text" /><button>倒叙</button>
<span></span>