详情参考:一步步用HTML5动手写个图片上传预览组件
H5中拖拽事件有:
[ - ] DragDrop：拖放完成，也就是鼠标拖入对象并在拖放区域释放。
[ - ] DragEnter ：拖放进入，也就是鼠标拖放对象进入拖放区域。
[ - ] DragLeave：离开拖放区域。
[ - ] DragOver ：拖放对象悬浮于拖放区域，在拖放区域内移动时多次触发。
1.拖拽文件获取文件信息
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
.example {
padding: 10px;
border: 1px solid #ccc;
}
#drop_zone {
border: 2px dashed #bbb;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
border-radius: 5px;
padding: 25px;
text-align: center;
font: 20pt bold 'Vollkorn';
color: #bbb;
}
</style>
</head>
<body>
<div class="example">
<div id="drop_zone">将文件拖放到此处</div>
<output id="list"></output>
</div>
<script>
function handleFileSelect(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
var files = evt.dataTransfer.files;//获取文件集
var output = [];
for(var i = 0, f; f = files[i]; i++) {
output.push('<li><strong>', escape(f.name), '</strong> (', f.type || 'n/a', ') - ',
f.size, ' bytes, last modified: ',
f.lastModifiedDate.toLocaleDateString(), '</li>');
}
document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}
function handleDragOver(evt) {
evt.stopPropagation();
evt.preventDefault();
evt.dataTransfer.dropEffect = 'copy';
}
var dropZone = document.getElementById('drop_zone');
dropZone.addEventListener('dragover', handleDragOver, false);
dropZone.addEventListener('drop', handleFileSelect, false);
//body中阻止 拖拽事件防止拖拽错误
document.body.addEventListener('dragover', function(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
return false;
}, false);
document.body.addEventListener('drop', function(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
return false;
}, false);
</script>
</body>
</html>
2.限制文件大小与文件格式
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
.example {
padding: 10px;
border: 1px solid #ccc;
}
#drop_zone {
border: 2px dashed #bbb;
-moz-border-radius: 5px;
-webkit-border-radius: 5px;
border-radius: 5px;
padding: 25px;
text-align: center;
font: 20pt bold 'Vollkorn';
color: #bbb;
}
</style>
</head>
<body>
<div class="example">
<div id="drop_zone">将文件拖放到此处</div>
<output id="list"></output>
</div>
<script>
function handleFileSelect(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
var files = evt.dataTransfer.files;//获取文件集
var output = [];
for(var i = 0, f; f = files[i]; i++) {
if(f.size<1024*1024*2&&(f.type=="image/png"||f.type=="image/jpeg")){//<===这里
output.push('<li><strong>', escape(f.name), '</strong> (', f.type || 'n/a', ') - ',
f.size, ' bytes, last modified: ',
f.lastModifiedDate.toLocaleDateString(), '</li>');
}
}
document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}
function handleDragOver(evt) {
evt.stopPropagation();
evt.preventDefault();
evt.dataTransfer.dropEffect = 'copy'; // Explicitly show this is a copy.
}
var dropZone = document.getElementById('drop_zone');
dropZone.addEventListener('dragover', handleDragOver, false);
dropZone.addEventListener('drop', handleFileSelect, false);
//body中阻止 拖拽事件防止拖拽错误
document.body.addEventListener('dragover', function(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
return false;
}, false);
document.body.addEventListener('drop', function(evt) {
evt.stopPropagation(); //阻止默认事件
evt.preventDefault(); //阻止默认事件
return false;
}, false);
</script>
</body>
</html>
3.显示缩略图与动态增删效果
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
<title>简易上传预览</title>
<style type="text/css">
#drop_zone {
display: block;
border: 2px dashed #BBB;
padding: 25px 5px;
text-align: center;
font-size: 20pt;
color: #BBB;
border-radius: 5px;
}
#drop_zone.hovering {
-webkit-box-shadow: inset 0px 0px 50px #BBB;
-moz-box-shadow: inset 0px 0px 50px #BBB;
-o-box-shadow: inset 0px 0px 50px #BBB;
box-shadow: inset 0px 0px 50px #BBB;
}
#file-upload-box {
margin: 40px 25px;
padding: 10px;
border: 1px solid #BBB;
}
#description:first-line {
margin-left: 42px;
}
#output_area {
text-align: center;
display: flex;
flex-wrap: wrap;
align-content: space-between;
position: absolute;
left: 0;
right: 0;
top: 106px;
overflow: auto;
bottom: 0;
}
#file-upload-box {
position: absolute;
top: 45px;
bottom: 45px;
left: 20px;
right: 20px;
background-color: #fff;
overflow: auto;
}
.upload-img-itme {
color: #333;
width: 170px;
margin: 10px;
color: #333;
flex: 1;
}
.upload-img-itme a.rimg-name {
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
padding: 5px;
display: block;
}
.d-image {
box-shadow: 0 0 10px #bbb;
border-radius: 20px;
overflow: hidden;
width: 170px;
height: 170px;
display: inline-block;
z-index: 344;
background-color: #cecece;
position: relative;
transition: all 1s;
-moz-transition: all 1s;
-webkit-transition: all 1s;
-o-transition: all 1s;
cursor: pointer;
}
.d-image:hover:after {
display: block;
}
.d-image:after {
content: "×";
font-size: 44px;
text-align: center;
width: 50%;
margin: auto;
position: absolute;
top: 50%;
display: none;
left: 50%;
-webkit-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);
}
.d-image:hover> img {
-webkit-filter: blur(5px);
-moz-filter: blur(5px);
-ms-filter: blur(5px);
filter: blur(5px);
}
</style>
</head>
<body ondrop="return false" ondragover="return false">
<!--防止拖拽跳转-->
<div id="file-upload">
<div id="file-upload-box">
<label id="drop_zone">将文件拖拽到这里或点击这里
<input multiple id="files" type="file" hidden="hidden" style="display: none;" name="files[]" />
</label>
<div id="output_area"></div>
</div>
</div>
<div style="position: absolute; bottom: 10px; left: 40px; right: 40px;text-align: center;">
<button onclick="demo.ImageLs=[];reloadDiv();" style="padding: 5px 10px; background: #fff; border: 1px #000 solid; cursor: pointer;">清空</button>
<button onclick="alert('上传')" style="padding: 5px 10px; background: #fff; border: 1px #000 solid; cursor: pointer;">上传</button>
</div>
<script>
var ImgType = ["gif", "jpeg", "jpg", "bmp", "png", "ico", "webp"];
function getFileUrl(fileObj) {
return window.URL.createObjectURL(fileObj);
}
//拖拽功能
var output = document.getElementById('output_area');
var dropZone = document.getElementById('drop_zone');
if(!(('draggable' in dropZone) && ('ondragenter' in dropZone) &&
('ondragleave' in dropZone) && ('ondragover' in dropZone) &&
window.File)) {
document.getElementById('error_msg').style.display = 'block';
document.getElementById('demo_area').style.display = 'none';
} else {
function handleFileDragEnter(e) {
e.stopPropagation();
e.preventDefault();
this.classList.add('hovering');
}
function handleFileDragLeave(e) {
e.stopPropagation();
e.preventDefault();
this.classList.remove('hovering');
}
function handleFileDragOver(e) {
e.stopPropagation();
e.preventDefault();
e.dataTransfer.dropEffect = 'copy';
}
function handleFileDrop(e) {
e.stopPropagation();
e.preventDefault();
this.classList.remove('hovering');
FilesGetImgSv(e.dataTransfer.files);
}
dropZone.addEventListener('dragenter', handleFileDragEnter, false);
dropZone.addEventListener('dragleave', handleFileDragLeave, false);
dropZone.addEventListener('dragover', handleFileDragOver, false);
dropZone.addEventListener('drop', handleFileDrop, false);
}
//<input
function handleFileSelect(evt) {
FilesGetImgSv(evt.target.files);
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
//图片文件 过滤 显示
function FilesGetImgSv(files) {//获取文件
for(var i = 0, f; f = files[i]; i++) {
if(RegExp("\.(" + ImgType.join("|") + ")$", "i").test(f.name.toLowerCase())) { //这里是简单后缀验证,可添加f.type验证格式
f.BolbUrl = getFileUrl(f);
demo.ImageLs.push(f);
}
}
reloadDiv();
}
function reloadDiv(){//刷新视图
var t="";
demo.ImageLs.forEach(function(v,i){
t=t+`<div class="upload-img-itme"><div class="d-image" onclick="demo.removeThisUpImg(${i})"></div><a class="rimg-name"><strong>${v.name}</strong></a></div>`;
});
document.getElementById("output_area").innerHTML=t;
}
var demo = {
ImageLs: [],
removeThisUpImg: function(index) {
demo.ImageLs.splice(index, 1);
reloadDiv();
}
};
</script>
</body>
</html>