多张图下载，下载图片，跨域的不可以
download.js源码
//download.js v4.21, by dandavis; 2008-2018. [MIT] see http://danml.com/download.html for tests/usage
// v1 landed a FF+Chrome compatible way of downloading strings to local un-named files, upgraded to use a hidden frame and optional mime
// v2 added named files via a[download], msSaveBlob, IE (10+) support, and window.URL support for larger+faster saves than dataURLs
// v3 added dataURL and Blob Input, bind-toggle arity, and legacy dataURL fallback was improved with force-download mime and base64 support. 3.1 improved safari handling.
// v4 adds AMD/UMD, commonJS, and plain browser support
// v4.1 adds url download capability via solo URL argument (same domain/CORS only)
// v4.2 adds semantic variable names, long (over 2MB) dataURL support, and hidden by default temp anchors
// https://github.com/rndme/download
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
// AMD. Register as an anonymous module.
define([], factory);
} else if (typeof exports === 'object') {
// Node. Does not work with strict CommonJS, but
// only CommonJS-like environments that support module.exports,
// like Node.
module.exports = factory();
} else {
// Browser globals (root is window)
root.download = factory();
}
}(this, function () {
return function download(data, strFileName, strMimeType) {
var self = window, // this script is only for browsers anyway...
defaultMime = "application/octet-stream", // this default mime also triggers iframe downloads
mimeType = strMimeType || defaultMime,
payload = data,
url = !strFileName && !strMimeType && payload,
anchor = document.createElement("a"),
toString = function(a){return String(a);},
myBlob = (self.Blob || self.MozBlob || self.WebKitBlob || toString),
fileName = strFileName || "download",
blob,
reader;
myBlob= myBlob.call ? myBlob.bind(self) : Blob ;
if(String(this)==="true"){ //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
payload=[payload, mimeType];
mimeType=payload[0];
payload=payload[1];
}
if(url && url.length< 2048){ // if no filename and no mime, assume a url was passed as the only argument
fileName = url.split("/").pop().split("?")[0];
anchor.href = url; // assign href prop to temp anchor
if(anchor.href.indexOf(url) !== -1){ // if the browser determines that it's a potentially valid url path:
var ajax=new XMLHttpRequest();
ajax.open( "GET", url, true);
ajax.responseType = 'blob';
ajax.onload= function(e){
download(e.target.response, fileName, defaultMime);
};
setTimeout(function(){ ajax.send();}, 0); // allows setting custom ajax headers using the return:
return ajax;
} // end if valid url?
} // end if url?
//go ahead and download dataURLs right away
if(/^data:([w+-]+/[w+.-]+)?[,;]/.test(payload)){
if(payload.length > (1024*1024*1.999) && myBlob !== toString ){
payload=dataUrlToBlob(payload);
mimeType=payload.type || defaultMime;
}else{
return navigator.msSaveBlob ? // IE10 can't do a[download], only Blobs:
navigator.msSaveBlob(dataUrlToBlob(payload), fileName) :
saver(payload) ; // everyone else can save dataURLs un-processed
}
}else{//not data url, is it a string with special needs?
if(/([x80-xff])/.test(payload)){
var i=0, tempUiArr= new Uint8Array(payload.length), mx=tempUiArr.length;
for(i;i<mx;++i) tempUiArr[i]= payload.charCodeAt(i);
payload=new myBlob([tempUiArr], {type: mimeType});
}
}
blob = payload instanceof myBlob ?
payload :
new myBlob([payload], {type: mimeType}) ;
function dataUrlToBlob(strUrl) {
var parts= strUrl.split(/[:;,]/),
type= parts[1],
indexDecoder = strUrl.indexOf("charset")>0 ? 3: 2,
decoder= parts[indexDecoder] == "base64" ? atob : decodeURIComponent,
binData= decoder( parts.pop() ),
mx= binData.length,
i= 0,
uiArr= new Uint8Array(mx);
for(i;i<mx;++i) uiArr[i]= binData.charCodeAt(i);
return new myBlob([uiArr], {type: type});
}
function saver(url, winMode){
if ('download' in anchor) { //html5 A[download]
anchor.href = url;
anchor.setAttribute("download", fileName);
anchor.className = "download-js-link";
anchor.innerHTML = "downloading...";
anchor.style.display = "none";
anchor.addEventListener('click', function(e) {
e.stopPropagation();
this.removeEventListener('click', arguments.callee);
});
document.body.appendChild(anchor);
setTimeout(function() {
anchor.click();
document.body.removeChild(anchor);
if(winMode===true){setTimeout(function(){ self.URL.revokeObjectURL(anchor.href);}, 250 );}
}, 66);
return true;
}
// handle non-a[download] safari as best we can:
if(/(Version)/(d+).(d+)(?:.(d+))?.*Safari//.test(navigator.userAgent)) {
if(/^data:/.test(url)) url="data:"+url.replace(/^data:([w/-+]+)/, defaultMime);
if(!window.open(url)){ // popup blocked, offer direct download:
if(confirm("Displaying New Document
Use Save As... to download, then click back to return to this page.")){ location.href=url; }
}
return true;
}
//do iframe dataURL download (old ch+FF):
var f = document.createElement("iframe");
document.body.appendChild(f);
if(!winMode && /^data:/.test(url)){ // force a mime that will download:
url="data:"+url.replace(/^data:([w/-+]+)/, defaultMime);
}
f.src=url;
setTimeout(function(){ document.body.removeChild(f); }, 333);
}//end saver
if (navigator.msSaveBlob) { // IE10+ : (has Blob, but not a[download] or URL)
return navigator.msSaveBlob(blob, fileName);
}
if(self.URL){ // simple fast and modern way using Blob and URL:
saver(self.URL.createObjectURL(blob), true);
}else{
// handle non-Blob()+non-URL browsers:
if(typeof blob === "string" || blob.constructor===toString ){
try{
return saver( "data:" + mimeType + ";base64," + self.btoa(blob) );
}catch(y){
return saver( "data:" + mimeType + "," + encodeURIComponent(blob) );
}
}
// Blob but not URL support:
reader=new FileReader();
reader.onload=function(e){
saver(this.result);
};
reader.readAsDataURL(blob);
}
return true;
}; /* end download() */
}));
// 匹配后缀
function getFileType(fileName) {
// 后缀获取
let suffix = '';
// 获取类型结果
let result = '';
try {
const flieArr = fileName.split('.');
suffix = flieArr[flieArr.length - 1];
} catch (err) {
suffix = '';
}
// fileName无后缀返回 false
if (!suffix) { return false; }
suffix = suffix.toLocaleLowerCase();
// 图片格式
const imglist = ['png', 'jpg', 'jpeg', 'bmp', 'gif'];
// 进行图片匹配
result = imglist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'image';
}
// 匹配txt
const txtlist = ['txt'];
result = txtlist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'txt';
}
// 匹配 excel
const excelist = ['xls', 'xlsx'];
result = excelist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'excel';
}
// 匹配 word
const wordlist = ['doc', 'docx'];
result = wordlist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'word';
}
// 匹配 pdf
const pdflist = ['pdf'];
result = pdflist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'pdf';
}
// 匹配 ppt
const pptlist = ['ppt', 'pptx'];
result = pptlist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'ppt';
}
// 匹配 视频
const videolist = ['mp4', 'm2v', 'mkv', 'rmvb', 'wmv', 'avi', 'flv', 'mov', 'm4v'];
result = videolist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'video';
}
// 匹配 音频
const radiolist = ['mp3', 'wav', 'wmv'];
result = radiolist.find(function (obj) { return obj.item== suffix;});
if (result) {
return 'radio';
}
// 其他 文件类型
return 'other';
}
function downloadfile(url, strFileName, strMimeType) {
var xmlHttp = null;
if (window.ActiveXObject) {
// IE6, IE5 浏览器执行代码
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} else if (window.XMLHttpRequest) {
// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
xmlHttp = new XMLHttpRequest();
}
//2.如果实例化成功，就调用open（）方法：
if (xmlHttp != null) {
xmlHttp.open("get", url, true);
xmlHttp.responseType = 'blob';//关键
xmlHttp.send();
xmlHttp.onreadystatechange = doResult; //设置回调函数
}
function doResult() {
if (xmlHttp.readyState == 4) { //4表示执行完成
if (xmlHttp.status == 200) { //200表示执行成功
download(xmlHttp.response, strFileName, strMimeType);
loadings_hide();
$("#lodings_pic").hide()
}
}
}
}
先引入上面download.js源码
//下载多张图
pic= ["img.png","img.png"];
btns.onclick = function name(params) {
for (let index = 0; index < pic.length; index++) {
let timestamp = new Date().getTime();//当前时间
downloadfile(pic[index], timestamp, getFileType(timestamp))
timestamp++;
}
}
//下载一张图
btns.onclick = function name(params) {
downloadfile(src, timestamp, getFileType(timestamp))
}
原文链接：https://www.cnblogs.com/adingfirstlove/p/12856264.html