jQuery实现html元素拖拽

<div>
  <div class="money-input">
    定投金额 :
    <div class="input-rela">
      <input type="text" placeholder="2000"/>
      <span>元</span>
    </div>

  </div>
  <div class="money-line">
    <img index="js-minus-a" class="js-minus" src="../images/minus.png" alt=""/>
    <img id="dragImg" class="red-rela" src="../images/money-dw.png" alt="" onDrag="drag(event)" onDragEnd="dragEnd(event)" style="left: 265px;"/>
    <img id="dragLine" class="line3" src="../images/money-line.png" alt=""/>
    <img index="js-plus-a" class="js-plus" src="../images/plus.png" alt="" style="margin-left: 880px;"/>
  </div>
  <div class="money-desc">
    <span style="margin-left: 65px;">100</span>
    <span>500</span>
    <span>1000</span>
    <span>2000</span>
    <span>3000</span>
    <span>4000</span>
    <span>5000</span>
    <span>6000</span>
    <span>7000</span>
    <span>8000</span>
    <span>9000</span>
    <span>10000</span>
  </div>
  <p>单位:元</p>
</div>

 .money-input{margin:36px auto 0;width:330px;font-size:14px;color:#818181}
 .input-rela{width:250px;height:42px;display:inline-block;position:relative}
 .input-rela>input{width:inherit;height:38px;border:1px solid #eee}
 .input-rela>span{position:absolute;right:10px;top:13px}
 .money-line{width:970px;margin:60px auto 0;position:relative}
 .line3{position:absolute;left:40px;top:10px}
 .red-rela{position:absolute;top:0;z-index:2;cursor:pointer}
 .money-desc,.month-desc{font-size:12px;color:#818181}
 .money-desc+p,.month-desc+p{margin-right:60px;text-align:right;color:#5a5a5a}
 .money-desc>span{display:inline-block;width:71px}
 .month-desc>span{display:inline-block;width:79px}

/**
* Created by cq on 2015/6/15.
*/
$(function(){

  $('.js-minus').click(function(){
    /* min need calculate*/
    var index = $(this).attr("index")
    var move,min;
    if(index=="js-minus-a"){
      move = 77;
      min = 34;
    }
    if(index=="js-minus-b"){
      move = 85;
      min = 36;
    }
    var redPoint = $(this).next()
    var left = redPoint.css("left")
    var leftInt = left.replace(/px/g,"")
    if((parseInt(leftInt)-move)>=min){
      var newLeft = (parseInt(leftInt)-move)+"px"
      redPoint.css("left",newLeft)
      var num = parseInt ( (parseInt(leftInt)-move-min) / move )
      var input = $(this).parent().prev().find("input")
      if(index=="js-minus-a"){
        var spans = $(this).parent().next().find("span")
        var html = spans.eq(num).html()
        input.val(html)
      }
      if(index=="js-minus-b"){
        input.val(getMonth(num))
      }
    }
  })

  $('.js-plus').click(function(){
    /* max and min need calculate*/
    var index = $(this).attr("index")
    var move , max , min ;
    if(index=="js-plus-a"){
      move = 77; //ÿ��ƫ����
      max = 881; //��������
      min = 34; //��Сƫ����
    }
    if(index=="js-plus-b"){
      move = 85;
      max = 886;
      min = 36;
    }

    var redPoint = $(this).prev().prev()
    var left = redPoint.css("left")
    var leftInt = left.replace(/px/g,"")
    if((parseInt(leftInt)+move)<=max){
      var newLeft = (parseInt(leftInt)+move)+"px"
      redPoint.css("left",newLeft)
      var num = parseInt( (parseInt(leftInt)+move-min) / move )
      var input = $(this).parent().prev().find("input")
      if(index=="js-plus-a"){
        var spans = $(this).parent().next().find("span")
        var html = spans.eq(num).html()
        input.val(html)
      }
      if(index=="js-plus-b"){
        input.val(getMonth(num))
      }
    }
  })

  /*move img js*/
  var offsetx = 0, offsety = 0;
  var dragImg = document.getElementById("dragImg")
  dragImg.addEventListener("mousedown",beforeDrag,true);
})

function beforeDrag(ev){
  dragImg = ev.target;
  var l = dragImg.offsetLeft;
  var t = dragImg.offsetTop;
  offsetx = ev.clientX - l;
  offsety = ev.clientY - t;
}

function drag(e){
  e.preventDefault();
  /*min need calculate*/
  var ml = 8,mr = 20,maxy = 70,moveWidth = 77,min=34;
  var dragImg = e.target;
  var dragLine = document.getElementById("dragLine");
  var movex = e.clientX - offsetx;
  var movey = e.clientY - offsety;
  var minPY = dragLine.offsetLeft-ml;
  var maxPY = dragLine.offsetLeft+dragLine.clientWidth-mr;
  if(Math.abs(movey)>maxy){
    return
  }
  if(movex<minPY){
    dragImg.style.left = minPY + "px";
    return
  }
  if(movex>maxPY){
    dragImg.style.left = maxPY + "px";
    return
  }
  dragImg.style.left = movex + "px";

}

function dragEnd (e){
  e.preventDefault();
  /*min need calculate*/
  var ml = 8,mr = 20,maxy = 70,moveWidth = 77,min=34;
  var dragImg = e.target;
  var dragLine = document.getElementById("dragLine");
  var movex = e.clientX - offsetx;
  var movey = e.clientY - offsety;
  var minPY = dragLine.offsetLeft-ml;
  var maxPY = dragLine.offsetLeft+dragLine.clientWidth-mr;

  if(movex<minPY){
    dragImg.style.left = minPY + "px";
    $(dragImg).parent().prev().find("input").val(100)
    return
  }
  if(movex>maxPY){
    dragImg.style.left = maxPY + "px";
    $(dragImg).parent().prev().find("input").val(10000)
    return
  }
  /*dragEnd xifu*/
  var num = parseInt ( movex / moveWidth )
  dragImg.style.left = (min+moveWidth*num) + "px";
  /*dragEnd set input*/
  var thisNode = $(dragImg)
  var spans = thisNode.parent().next().find('span')
  var html = spans.eq(num).html()
  var input = thisNode.parent().prev().find("input")
  input.val(html)
}

/*
function init() {
document.body.onmousemove = function(e) {
if (!e) {
e = window.event;
}
else {
e.srcElement = e.target;
}
document.getElementById("divDebug").innerHTML = "mousemove (" + e.clientX + "," + e.clientY + ") srcElement=" + e.srcElement.tagName + "[" + e.srcElement.id + "]";
}
}*/