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html5之拖放的学习和完整实例代码

时间:2021-07-01 10:21:17 帮助过:18人阅读

本文学习html5的拖放并完整实例代码,希望对H5初学者有帮助!

1)创建来源项目

1.1)draggable属性的值:

true——此元素能被拖动;

false——此元素不能被拖动;

auto——浏览器能够自主决定某个元素能否被拖动;

1.2)被拖动元素的事件:

dragstart——在元素開始被拖动时触发;

drag——在元素被拖动时重复触发。

dragend——在拖动操作完毕时触发;

2)创建释放区

2.1)释放区事件:

dragenter——当被拖动元素进入释放区所占领的屏幕空间时触发;

dragover——当被拖动元素在释放区内触发时移动触发;

dragleave——当被拖动元素没有放入就离开释放区时触发;

drop——当被拖动元素在释放区放下时触发。

<!DOCTYPE HTML>
<html>
    <head>
        <title>Example</title>
        <style>
            #src > * {float:left;}
            #src > img {border: thin solid black; padding: 2px; margin:4px;}
            #target {border: thin solid black; margin:4px;}
            #target { height: 81px; width: 81px; text-align: center; display: table;}
            #target > p {display: table-cell; vertical-align: middle;}
            img.dragged {background-color: lightgrey;}
        </style>
    </head>
    <body>
        <p id="src">
            <img draggable="true" id="banana" src="banana100.png" alt="banana"/>
            <img draggable="true" id="apple" src="apple100.png" alt="apple"/>
            <img draggable="true" id="cherries" src="cherries100.png" alt="cherry"/>
            <p id="target">
                <p id="msg">Drop Here</p>
            </p>            
        </p>            
    
        <script>
            var src = document.getElementById("src");
            var target = document.getElementById("target");
            var msg = document.getElementById("msg");
          
            var draggedID;
          
            target.ondragenter = handleDrag;
            target.ondragover = handleDrag;
            
            function handleDrag(e) {
                e.preventDefault();
            }
            
            target.ondrop = function(e) {
                var newElem = document.getElementById(draggedID).cloneNode(false);
                target.innerHTML = "";
                target.appendChild(newElem);
                e.preventDefault();
            }
          
            src.ondragstart = function(e) {
                draggedID = e.target.id;
                e.target.classList.add("dragged");
            }
            
            src.ondragend = function(e) {
                var elems = document.querySelectorAll(".dragged");
                for (var i = 0; i < elems.length; i++) {
                    elems[i].classList.remove("dragged");
                }
            }          
        </script>
    </body>
</html>

3)使用DataTransfer对象

3.1)与拖放操作所触发的事件同一时候派发的对象是DragEvent,它派生于MouseEvent。

DragEvent对象定义的额外属性:

dataTransfer——返回用于数据传输到释放区的对象(DataTransfer);

3.2)DataTransfer对象定义的属性:

types——返回数据的格式。

getData(<format>)——返回指定格式的数据;

setData(<format>,<data>)——设置指定格式的数据。

clearData(<format>)——移除指定格式的数据。

files——返回已被拖动文件的列表。

<!DOCTYPE HTML>
<html>
    <head>
        <title>Example</title>
        <style>
            #src > * {float:left;}
            #src > img {border: thin solid black; padding: 2px; margin:4px;}
            #target {border: thin solid black; margin:4px;}
            #target { height: 81px; width: 81px; text-align: center; display: table;}
            #target > p {display: table-cell; vertical-align: middle;}
            img.dragged {background-color: lightgrey;}
        </style>
    </head>
    <body>
        <p id="src">
            <img draggable="true" id="banana" src="banana100.png" alt="banana"/>
            <img draggable="true" id="apple" src="apple100.png" alt="apple"/>
            <img draggable="true" id="cherries" src="cherries100.png" alt="cherry"/>
            <p id="target">
                <p id="msg">Drop Here</p>
            </p>            
        </p>            
    
        <script>
            var src = document.getElementById("src");
            var target = document.getElementById("target");
                    
            target.ondragenter = handleDrag;
            target.ondragover = handleDrag;
            
            function handleDrag(e) {
                e.preventDefault();
            }
            
            target.ondrop = function(e) {
                var droppedID = e.dataTransfer.getData("Text");               
                var newElem = document.getElementById(droppedID).cloneNode(false);
                target.innerHTML = "";
                target.appendChild(newElem);
                e.preventDefault();
            }
          
            src.ondragstart = function(e) {
                e.dataTransfer.setData("Text", e.target.id);
                e.target.classList.add("dragged");
            }
            
            src.ondragend = function(e) {
                var elems = document.querySelectorAll(".dragged");
                for (var i = 0; i < elems.length; i++) {
                    elems[i].classList.remove("dragged");
                }
            }          
        </script>
    </body>
</html>

3.3)拖放文件:

File对象定义的属性

name——获取文件名称。

type——获取文件类型。以MIME类型表示;

size——获取文件大小(以字节计算);

<!DOCTYPE HTML>
<html>
    <head>
        <title>Example</title>
        <style>
            .table {display:table;}
            .row {display:table-row;}
            .cell {display: table-cell; padding: 5px;}
            .label {text-align: right;}
            #target {border: medium double black; margin:4px; height: 50px;
                width: 200px; text-align: center; display: table;}
            #target > p {display: table-cell; vertical-align: middle;}
        </style>
    </head>
    <body>
        <form id="fruitform" method="post" action="http://titan:8080/form">
            <p class="table">
                <p class="row">
                    <p class="cell label">Bananas:</p>
                    <p class="cell"><input name="bananas" value="2"/></p>
                </p>
                <p class="row">
                    <p class="cell label">Apples:</p>
                    <p class="cell"><input name="apples" value="5"/></p>
                </p>
                <p class="row">
                    <p class="cell label">Cherries:</p>
                    <p class="cell"><input name="cherries" value="20"/></p>
                </p>
                <p class="row">
                    <p class="cell label">File:</p>
                    <p class="cell"><input type="file" name="file"/></p>
                </p>
                <p class="row">
                    <p class="cell label">Total:</p>
                    <p id="results" class="cell">0 items</p>
                </p>                
            </p>
            <p id="target">
                <p id="msg">Drop Files Here</p>
            </p>            
            <button id="submit" type="submit">Submit Form</button>
        </form>
        <script>
            var target = document.getElementById("target");     
            var httpRequest;
            var fileList;
                         
            document.getElementById("submit").onclick = handleButtonPress;                    
            target.ondragenter = handleDrag;
            target.ondragover = handleDrag;
            
            function handleDrag(e) {
                e.preventDefault();
            }
            
            target.ondrop = function(e) {
                fileList = e.dataTransfer.files;
                e.preventDefault();
            }          
                         
            function handleButtonPress(e) {
                e.preventDefault();
                 
                var form = document.getElementById("fruitform");
                var formData = new FormData(form);
                 
                if (fileList || true) {
                    for (var i = 0; i < fileList.length; i++) {
                        formData.append("file" + i, fileList[i]);
                    }
                }  
                 
                httpRequest = new XMLHttpRequest();
                httpRequest.onreadystatechange = handleResponse;
                httpRequest.open("POST", form.action);
                httpRequest.send(formData);
            }
                         
            function handleResponse() {
                if (httpRequest.readyState == 4 && httpRequest.status == 200) {
                    var data = JSON.parse(httpRequest.responseText);
                    document.getElementById("results").innerHTML = "You ordered "
                        + data.total + " items";
                }
            }
         </script>
    </body>
</html>

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