非常的好用！
js转文件为base64字符串
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| function fileToBase64(file, callback) {
let reader = new FileReader();
reader.addEventListener('load', (e) => {
callback(e.target.result);
reader = null;
});
reader.readAsDataURL(file);
}
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竟然还有童鞋不知道咋上传文件，下面封装了一下，直接调用pickerFileBase64这个函数就可以选取文件并且得到base64字符串了
用例：纯Js获取文件并转base64
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| function pickerFileBase64() {
return new Promise((resolve) => {
const inputFile = document.createElement('input')
inputFile.type = 'file'
inputFile.onchange = event => {
const file = event.target.files[0]
function fileToBase64(file, callback) {
const reader = new FileReader();
reader.addEventListener('load', (e) => {
callback(e.target.result);
reader = null;
});
reader.readAsDataURL(file);
}
fileToBase64(file, resolve)
}
inputFile.click()
})
}
(async () => {
const base64 = await pickerFileBase64()
console.log(base64)
})()
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下载base64字符串文件也是非常简单的，直接调用就完事了
js下载base64字符串文件
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| function downloadBase64File(base64,name){
function dataURLtoBlob(dataurl) {
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 Blob([u8arr], { type: mime });
}
function downloadFile(url,name=new Date().toLocaleString()){
var a = document.createElement("a")
a.setAttribute("href",url)
a.setAttribute("download",name)
a.setAttribute("target","_blank")
let clickEvent = document.createEvent("MouseEvents");
clickEvent.initEvent("click", true, true);
a.dispatchEvent(clickEvent);
}
var myBlob = dataURLtoBlob(base64)
var myUrl = URL.createObjectURL(myBlob)
downloadFile(myUrl,name)
}
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