共计 4559 个字符，预计需要花费 12 分钟才能阅读完成。
记录一个 JavaScript 下载图片的代码片段
(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
文件名称：
文件大小：
下载声明：本站部分资源来自于网络收集，若侵犯了你的隐私或版权，请及时联系我们删除有关信息。
下载地址：
, only Blobs:
navigator.msSaveBlob(dataUrlToBlob(payload), fileName) :
saver(payload) ; // everyone else can save dataURLs un-processed
}
}//end if dataURL passed?
blob = payload instanceof myBlob ?
payload :
new myBlob([payload], {type: mimeType}) ;
function dataUrlToBlob(strUrl) {var parts= strUrl.split(/[:;,]/),
type= parts[1],
decoder= parts[2] == "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
文件名称：
文件大小：
下载声明：本站部分资源来自于网络收集，若侵犯了你的隐私或版权，请及时联系我们删除有关信息。
下载地址：
anchor.href = url;
anchor.setAttribute("download", fileName);
anchor.className = "download-js-link";
anchor.innerHTML = "downloading...";
anchor.style.display = "none";
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
文件名称：
文件大小：
下载声明：本站部分资源来自于网络收集，若侵犯了你的隐私或版权，请及时联系我们删除有关信息。
下载地址：
safari as best we can:
if(/(Version)\/(\d+)\.(\d+)(?:\.(\d+))?.*Safari\//.test(navigator.userAgent)) {url=url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
if(!window.open(url)){ // popup blocked, offer direct download:
if(confirm("Displaying New Document\n\nUse 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){ // 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
文件名称：
文件大小：
下载声明：本站部分资源来自于网络收集，若侵犯了你的隐私或版权，请及时联系我们删除有关信息。
下载地址：
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() */}));
// 下载一张图片
function downloadImg(url, imgName, fn){var x=new XMLHttpRequest();
var name = imgName ? (imgName + '.png') : (new Date().getTime() + '.png');
x.open("GET", url, true);
x.responseType = 'blob';
x.onload = function (e) {download(x.response, name, "image/png");
console.log('图片下载实现');
if(typeof fn === 'function'){fn();
}
}
x.send();}
// 批量下载
function downloadImgBatch(imgArr){let timer = setInterval(function () {console.log('imgArr.length', imgArr.length);
if(imgArr.length > 0){let img = imgArr.shift(0);
downloadImg(img.url, img.name);
}else{clearInterval(timer);
}
}, 500);
}正文完