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javascript - 如何修改此 HTML 和 JavaScript，使其在网页上提供多个可移动项目？

问题描述

我在网上找到了这段代码，它创建了一个可在屏幕上拖动的“卡片”。

我想添加更多卡片。我试着简单地制作更多的卡片，但这让我的卡片根本不动。

<!DOCTYPE html>

<html>

 <style>
body {
  background-image: url('background1.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
}
</style> 


<style>
#mydiv {
  position: absolute;
  z-index: 9;
  background-color: #f1f1f1;
  text-align: center;
  border: 1px solid #d3d3d3;
}

#mydivheader {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196F3;
  color: #fff;
}
</style>
<body>

<h1>Fun</h1>

<p>Click to move the card around</p>

<div id="mydiv">
  <div id="mydivheader">Click here</div>
  <p>This is a card with stuff on it.</p>
</div>


<script>
//Make the DIV element draggagle:
dragElement(document.getElementById("mydiv"));

function dragElement(elmnt) {
  var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;
  if (document.getElementById(elmnt.id + "header")) {
    /* if present, the header is where you move the DIV from:*/
    document.getElementById(elmnt.id + "header").onmousedown = dragMouseDown;
  } else {
    /* otherwise, move the DIV from anywhere inside the DIV:*/
    elmnt.onmousedown = dragMouseDown;
  }

  function dragMouseDown(e) {
    e = e || window.event;
    e.preventDefault();
    // get the mouse cursor position at startup:
    pos3 = e.clientX;
    pos4 = e.clientY;
    document.onmouseup = closeDragElement;
    // call a function whenever the cursor moves:
    document.onmousemove = elementDrag;
  }

  function elementDrag(e) {
    e = e || window.event;
    e.preventDefault();
    // calculate the new cursor position:
    pos1 = pos3 - e.clientX;
    pos2 = pos4 - e.clientY;
    pos3 = e.clientX;
    pos4 = e.clientY;
    // set the element's new position:
    elmnt.style.top = (elmnt.offsetTop - pos2) + "px";
    elmnt.style.left = (elmnt.offsetLeft - pos1) + "px";
  }

  function closeDragElement() {
    /* stop moving when mouse button is released:*/
    document.onmouseup = null;
    document.onmousemove = null;
  }
}
</script>

</body>
</html>

我怎样才能添加不止一张可移动的卡片？

标签： javascripthtml

解决方案

仅复制 html 的问题在于您还需要复制 css 和 javascript。最重要的是，您需要更改新元素的 id，否则一切都会一团糟。

这个例子不会教你很好的代码，而是回答你的问题：

//Make the DIV element draggagle:
dragElement(document.getElementById("mydiv"));
dragElement(document.getElementById("mydiv2"));

function dragElement(elmnt) {
  var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;
  if (document.getElementById(elmnt.id + "header")) {
    /* if present, the header is where you move the DIV from:*/
    document.getElementById(elmnt.id + "header").onmousedown = dragMouseDown;
  } else {
    /* otherwise, move the DIV from anywhere inside the DIV:*/
    elmnt.onmousedown = dragMouseDown;
  }

  function dragMouseDown(e) {
    e = e || window.event;
    e.preventDefault();
    // get the mouse cursor position at startup:
    pos3 = e.clientX;
    pos4 = e.clientY;
    document.onmouseup = closeDragElement;
    // call a function whenever the cursor moves:
    document.onmousemove = elementDrag;
  }

  function elementDrag(e) {
    e = e || window.event;
    e.preventDefault();
    // calculate the new cursor position:
    pos1 = pos3 - e.clientX;
    pos2 = pos4 - e.clientY;
    pos3 = e.clientX;
    pos4 = e.clientY;
    // set the element's new position:
    elmnt.style.top = (elmnt.offsetTop - pos2) + "px";
    elmnt.style.left = (elmnt.offsetLeft - pos1) + "px";
  }

  function closeDragElement() {
    /* stop moving when mouse button is released:*/
    document.onmouseup = null;
    document.onmousemove = null;
  }
}
#mydiv {
  position: absolute;
  z-index: 9;
  background-color: #f1f1f1;
  text-align: center;
  border: 1px solid #d3d3d3;
}

#mydivheader {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196F3;
  color: #fff;
}

#mydiv2 {
  position: absolute;
  z-index: 9;
  background-color: #f1f1f1;
  text-align: center;
  border: 1px solid #d3d3d3;
}

#mydivheader2 {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196F3;
  color: #fff;
}
<h1>Fun</h1>

<p>Click to move the card around</p>

<div id="mydiv">
  <div id="mydivheader">Click here</div>
  <p>This is a card with stuff on it.</p>
</div>

<div id="mydiv2">
  <div id="mydivheader2">Click here</div>
  <p>This is a card with stuff on it.</p>
</div>

但是您最好使用基于类的脚本。这将为您提供更少的冗余代码。

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