html

  <input id="orderNum1" name="orderNum1" class="form-control orderNum" type="number"  step="1" min="1" max="100" style="width: 50px" />
  <input id="orderNum2" name="orderNum2" class="form-control orderNum" type="number"  step="1" min="1" max="100" style="width: 50px" />
  <input id="orderNum3" name="orderNum3" class="form-control orderNum" type="number"  step="1" min="1" max="100" style="width: 50px" />

获取所有拥有orderNum属性标签的ID

  var indexStr = $('.orderNum').map(function(){return this.id}).get().join();
  var indexArray = indexStr.split(",");
  console.log("indexArray---"+indexArray)
  for(var i in indexArray){
      var indexStr = indexArray[i];
      var index = indexStr.substring(indexStr.indexOf('m')+1,indexStr.length);
      console.log("index---"+index)
  }