需求
支持文件转为base64，base64转blob，blob下载为文件
代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<h2>base64 to file</h2>
<textarea name="" id="text-area" cols="30" rows="10" style='width:100%;height: 200px;' placeholder="Paste base64 string here"></textarea>
<button class="download-btn" style='width: 150px;height:50px;display: block;margin:10px auto;'>Download</button>
<script>
/**
* 上传附件转base64
* @param {File} file 文件流
*/
const fileByBase64 = (file, callback) => {
var reader = new FileReader();
// 传入一个参数对象即可得到基于该参数对象的文本内容
reader.readAsDataURL(file);
reader.onload = function (e) {
// target.result 该属性表示目标对象的DataURL
console.log(e.target.result);
callback(e.target.result)
};
}
/**
* base64转Blob
* @param {*} data
*/
const base64ByBlob = (base64, callback) => {
var arr = base64.split(','), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
console.log(new Blob([u8arr], { type: mime }))
callback(new Blob([u8arr], { type: mime }))
}
document.querySelector('.download-btn').addEventListener('click',function(e) {
const base64 = document.querySelector('.text-area').inneerText;
// fileByBase64(file, (base64) => {
base64ByBlob(base64, (blob) => {
// var url = window.URL.createObjectURL(blob)
const fileName = `${new Date().valueOf()}.txt`;
const link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = fileName;
link.click();
window.URL.revokeObjectURL(link.href);
})
// })
})
</script>
</body>
</html>