example of how read an image from the server as a binary one and parse it to its base64 string

requestImageAsString.ts

const readImageAsDataURL = async (imageBlob: Blob): Promise<string> => {
	// https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsDataURL
	const imageReader = new FileReader();
	return new Promise<string>(resolve => {
		const load = () => {
			imageReader.removeEventListener('load', load);
			resolve(imageReader.result as string);
		};
		imageReader.addEventListener('load', load, false);
		imageReader.readAsDataURL(imageBlob);
	});
};

const requestImage = async (imageUrl: string): Promise<string> => {
	const MimeType = 'image/jpg, image/png';
	const headers = {
		Accept: MimeType,
		['Content-Type']: MimeType
	};

	try {
		const response = await fetch(`https://cors-anywhere.herokuapp.com/${imageUrl}`, {
			method: 'GET',
			headers
		});

		if (!response.ok) {
			throw response;
		}

		let output = '';
		try {
			const blob = await response.blob();
			output = await readImageAsDataURL(blob);
		} catch (e) {}
		return output;
	} catch (error) {
		throw error;
	}
};