如何在 JavaScript 中将 Blob 转换为文件
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How to convert Blob to File in JavaScript
提问by skip
I need to upload an image to NodeJS server to some directory. I am using connect-busboynode module for that.
我需要将图像上传到 NodeJS 服务器到某个目录。我正在connect-busboy为此使用节点模块。
I had the dataURLof the image that I converted to blob using the following code:
我dataURL使用以下代码将图像转换为 blob：
dataURLToBlob: function(dataURL) {
var BASE64_MARKER = ';base64,';
if (dataURL.indexOf(BASE64_MARKER) == -1) {
var parts = dataURL.split(',');
var contentType = parts[0].split(':')[1];
var raw = decodeURIComponent(parts[1]);
return new Blob([raw], {type: contentType});
}
var parts = dataURL.split(BASE64_MARKER);
var contentType = parts[0].split(':')[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;
var uInt8Array = new Uint8Array(rawLength);
for (var i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
}
return new Blob([uInt8Array], {type: contentType});
}
I need a way to convert the blob to a file to upload the image.
我需要一种方法将 blob 转换为文件以上传图像。
Could somebody help me with it?
有人可以帮我吗？
回答by Joshua P Nixon
You can use the File constructor:
您可以使用 File 构造函数：
var file = new File([myBlob], "name");
As per the w3 specification this will append the bytes that the blob contains to the bytes for the new File object, and create the file with the specified name http://www.w3.org/TR/FileAPI/#dfn-file
根据 w3 规范，这会将 blob 包含的字节附加到新 File 对象的字节中，并创建具有指定名称http://www.w3.org/TR/FileAPI/#dfn-file的文件
回答by CBarr
This function converts a Blobinto a Fileand it works great for me.
此函数将 a 转换Blob为 a File，对我来说效果很好。
Vanilla JavaScript
原生 JavaScript
function blobToFile(theBlob, fileName){
//A Blob() is almost a File() - it's just missing the two properties below which we will add
theBlob.lastModifiedDate = new Date();
theBlob.name = fileName;
return theBlob;
}
TypeScript(with proper typings)
TypeScript（具有正确的类型）
public blobToFile = (theBlob: Blob, fileName:string): File => {
var b: any = theBlob;
//A Blob() is almost a File() - it's just missing the two properties below which we will add
b.lastModifiedDate = new Date();
b.name = fileName;
//Cast to a File() type
return <File>theBlob;
}
Usage
用法
var myBlob = new Blob();
//do stuff here to give the blob some data...
var myFile = blobToFile(myBlob, "my-image.png");
回答by mili
Joshua P Nixon's answer is correct but I had to set last modified date also. so here is the code.
Joshua P Nixon的回答是正确的，但我也必须设置上次修改日期。所以这是代码。
var file = new File([blob], "file_name", {lastModified: 1534584790000});
1534584790000is an unix timestamp for "GMT: Saturday, August 18, 2018 9:33:10 AM"
1534584790000是Unix时间戳“ GMT：星期六，2018年8月18日上午09点33分十秒”
回答by DAVID _
My modernvariant:
我的现代变体：
function blob2file(blobData) {
const fd = new FormData();
fd.set('a', blobData);
return fd.get('a');
}
回答by Alexandre Daubricourt
For me to work I had to explicitly provide the typealthough it is contained in the blob by doing so:
为了让我工作，我必须明确提供类型，尽管它包含在 blob 中：
const file = new File([blob], 'untitled', { type: blob.type })
回答by Moslem Shahsavan
Use saveAson FileSaver.jsgithub project.
使用saveAs上FileSaver.jsgithub上的项目。
FileSaver.jsimplements the saveAs()FileSaver interface in browsers that do not natively support it.
FileSaver.jssaveAs()在本机不支持它的浏览器中实现FileSaver 接口。
