如何将Base64字符串转换为JavaScript文件对象,如从文件输入形式? [英] How to convert Base64 String to javascript file object like as from file input form?
问题描述
我想将从文件中提取的Base64String(例如:AAAAA ....〜)转换为javascript文件对象。
javascript文件对象意思是这样的代码:
HTML:
< input type =fileid =selectFile>
JS:
< code $('#selectFile')。on('change',function(e){
var file = e.target.files [0];
console。日志(文件)
}
我只想通过解码base64字符串(由其他应用程序从文件编码)获取文件对象,而无需html文件输入表单。
谢谢。
方式1:只适用于dataURL,不适用于其他类型的url。
$ p $
function dataURLtoFile(dataurl,filename ){
var arr = dataurl.split(','),mime = arr [0] .match(/:(。*?); /)[1],
bstr = atob(arr [n]); n = bstr.length,u8arr = new Uint8Array(n);
while(n - ){
u8arr [n] = bstr.charCodeAt(n);
}
返回新文件([u8arr],文件名,{ty例如:
var file = dataURLtoFile('data:text / plain; base64,aGVsbG8gd29ybGQ =','hello.txt );
console.log(file);
方式2:适用于任何类型的网址(http url, dataURL,blobURL等)
//返回一个用File实例解析的promise
function urltoFile (函数(buf))(函数(res){返回res.arrayBuffer();})
.then(函数(buf) {return new File([buf],filename,{type:mimeType});})
);
}
//用法示例:
urltoFile('data:text / plain; base64,aGVsbG8gd29ybGQ =','hello.txt','text / plain')
.then(函数(文件){
console.log(文件);
})
I want to convert Base64String extracted from file(ex: "AAAAA....~") to a javascript file object.
The javascript file object what I mean is like this code:
HTML:
<input type="file" id="selectFile" >
JS:
$('#selectFile').on('change', function(e) {
var file = e.target.files[0];
console.log(file)
}
'file' variable is a javascript file object. So I want to convert a base64 string to the javascript file object like that.
I just want to get file object by decoding base64 string (encoded by other app from a file) without html file input form.
Thank you.
Way 1: only works for dataURL, not for other types of url.
function dataURLtoFile(dataurl, filename) {
var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
while(n--){
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, {type:mime});
}
//Usage example:
var file = dataURLtoFile('data:text/plain;base64,aGVsbG8gd29ybGQ=', 'hello.txt');
console.log(file);
Way 2: works for any type of url, (http url, dataURL, blobURL, etc...)
//return a promise that resolves with a File instance
function urltoFile(url, filename, mimeType){
return (fetch(url)
.then(function(res){return res.arrayBuffer();})
.then(function(buf){return new File([buf], filename, {type:mimeType});})
);
}
//Usage example:
urltoFile('data:text/plain;base64,aGVsbG8gd29ybGQ=', 'hello.txt', 'text/plain')
.then(function(file){
console.log(file);
})
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