base64 文件上傳前端

關鍵代碼：

// 將base64 的數據弄到form表單中
// 將base64 的代碼轉化為二進制
let bytes = window.atob(crop_base64.split(',')[1]);
let ab = new ArrayBuffer(bytes.length);
let ia = new Int8Array(ab);
for (let i = 0; i < bytes.length; ++ i) {
    ia[i] = bytes.charCodeAt(i);
}
let blob = new Blob([ia], {type: 'image/jpeg'});
let file_name = new Date();
blob.name = file_name + '.jpg';
blob.lastModifiedDate = file_name;
console.log(blob);
let form = document.getElementById('crop_form');
let form_data = new FormData(form);
// 將數據弄到 form 表單中
form_data.append('crop_file', blob, file_name);