Here's the Typescript version of Abubakar Ahmad's answer
function imageTo64(
url: string,
callback: (path64: string | ArrayBuffer) => void
): void {
const xhr = new XMLHttpRequest();
xhr.open('GET', url);
xhr.responseType = 'blob';
xhr.send();
xhr.onload = (): void => {
const reader = new FileReader();
reader.readAsDataURL(xhr.response);
reader.onloadend = (): void => callback(reader.result);
}
}