Chunked file upload

FileToUpload.ts

export default class FileToUpload {
    static chunkSize = 1000000;
    static uploadUrl = 'http://localhost:8080/api/v1/photo';
    readonly request: XMLHttpRequest;
    readonly file: File;
    currentChunkStartByte: number;
    currentChunkFinalByte: number;

    constructor(file: File, name: string) {
        this.request = new XMLHttpRequest();
        this.request.overrideMimeType('application/octet-stream');

        this.file = file;
        this.currentChunkStartByte = 0;
        this.currentChunkFinalByte = FileToUpload.chunkSize > this.file.size ? this.file.size : FileToUpload.chunkSize;
    }

    uploadFile() {
        this.request.open('POST', FileToUpload.uploadUrl, true);

        let chunk: Blob = this.file.slice(this.currentChunkStartByte, this.currentChunkFinalByte);
        this.request.setRequestHeader('Content-Range', `bytes ${this.currentChunkStartByte}-${this.currentChunkFinalByte}/${this.file.size}`);
        
        this.request.onload = () => {
            const remainingBytes = this.file.size - this.currentChunkFinalByte;
            
            if(this.currentChunkFinalByte === this.file.size) {
                alert('Yay, download completed! Chao!');
                return;
            } else if (remainingBytes < FileToUpload.chunkSize) {
                this.currentChunkStartByte = this.currentChunkFinalByte;
                this.currentChunkFinalByte = this.currentChunkStartByte + remainingBytes;
            }
            else {
                this.currentChunkStartByte = this.currentChunkFinalByte;
                this.currentChunkFinalByte = this.currentChunkStartByte + FileToUpload.chunkSize;
            }

            this.uploadFile();
        }

        const formData = new FormData();
        formData.append('file', chunk, this.file.name); 
        this.request.send(formData);
    }
}

FileToUpload0.ts

class FileToUpload {
    static chunkSize = 1000000;
    static uploadUrl = 'http://localhost:8080/api/v1/photo';
    readonly request: XMLHttpRequest;
    readonly file: File;
    readonly name: string;
    currentChunkStartByte: number;
    currentChunkFinalByte: number;

    constructor(file: File, name: string) {
        this.request = new XMLHttpRequest();
        this.request.overrideMimeType('application/octet-stream');

        this.file = file;
        this.name = name;

        this.currentChunkStartByte = 0;
        this.currentChunkFinalByte = FileToUpload.chunkSize > this.file.size ? this.file.size : FileToUpload.chunkSize;
    }
}

main0.go

package main

import (
	"cloud.google.com/go/storage"
	"fmt"
	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
	"io"
	"os"
	"strconv"
	"strings"
)

func main() {
	router := gin.Default()

	config := cors.DefaultConfig()
	config.AllowAllOrigins = true
	config.AllowHeaders = []string{"Content-Type", "Content-Length", "Content-Range", "Accept-Encoding", "X-CSRF-Token", "Authorization", "accept", "origin", "Cache-Control", "X-Requested-With"}
	router.Use(cors.New(config))

	rg := router.Group("api/v1")
	{
		rg.POST("/photo", uploadFile)
	}

	router.Run()
}

uploadMediaComponent.tsx

import React, { useState } from 'react';
import './uploadMediaComponent.css';
import FileToUpload from './FileToUpload';

const UploadMediaComponent: React.FC = () => {
    const [filesToUpload, setFilesToUpload] = useState([] as FileToUpload[]);

    const onFileChange = (e: React.ChangeEvent<HTMLInputElement>) => {
        const files: FileList | null = e.target.files;
        if(!files) return;

        let filesToUpload: FileToUpload[] = [];
        for (let i = 0; i < files.length; i++) {
            filesToUpload.push(new FileToUpload(files[i], files[i].name));
        }

        setFilesToUpload(filesToUpload);
    };

    const onFormSubmit = (e: React.FormEvent<HTMLFormElement>) => {
        e.preventDefault();

        for (let i = 0; i < filesToUpload.length; i++) {
            filesToUpload[i].uploadFile();
        }
    };

    return (
        <div className="upload-container">
            <h2 className="upload-title">File Uploader</h2>
            <div className="upload-form">
                <form id="file_upload" onSubmit={onFormSubmit}>
                    <div className="upload-file-select">
                        <label htmlFor="file_1">Select files for upload</label>
                        <input id="file_1" type="file" multiple onChange={onFileChange}/>
                    </div>

                    <div className="upload-file-list">
                        {filesToUpload.map((f,i) => <div className="upload-file" key={i}>{f.file.name} - {f.file.size}bytes</div>)}
                    </div>

                    <div className="upload-submit">
                        <input type="submit" value="submit"/>
                    </div>
                </form>
            </div>
        </div>    
    )
}

UploadMediaComponent.displayName = 'UploadMedia';
export default UploadMediaComponent;

uploadMediaComponent0.tsx

    const UploadMediaComponent: React.FC = () => {
    
    return (
        <div className="upload-container">
            <h2 className="upload-title">File Uploader</h2>
            <div className="upload-form">
                <form id="file_upload" onSubmit={onFormSubmit}>
                    <div className="upload-file-select">
                        <label htmlFor="file_1">Select files for upload</label>
                        <input id="file_1" type="file" multiple onChange={onFileChange}/>
                    </div>

                    <div className="upload-file-list">
                        {filesToUpload.map((f,i) => <div className="upload-file" key={i}>{f.name} - {f.file.size}bytes</div>)}
                    </div>

                    <div className="upload-submit">
                        <input type="submit" value="submit"/>
                    </div>
                </form>
            </div>
        </div>    
    )
}

UploadMediaComponent.displayName = 'UploadMedia';
export default UploadMediaComponent;

how looks uploadFile in golang with the chunking?