canvas.js

    const reader = (blob) => {
        return new Promise((resolve, reject) => {
            const reader = new FileReader()
            reader.onloadend = () => resolve(reader.result)
            reader.onerror = reject
            reader.readAsDataURL(blob)
        })
    }

    const toDataURL = async (url) => {
        const FETCH = await fetch(url);
        const BLOB = await FETCH.blob();
        return await reader(BLOB);
    }
    
    toDataURL('https://www.gravatar.com/avatar/d50c83cc0c6523b4d3f6085295c953e0')
        .then(dataUrl => {
            console.log('RESULT:', dataUrl)
        })