compressAndBase64.js

async function compressAndBase64(file, {
    quality = 91,
    scaleFactor = Math.log(file.size) / 13, // scale down images over 1MB
} = {}) {
    return new Promise((res, rej)=>{
        const img = new Image();
        img.src = URL.createObjectURL(file);
        img.onload = function() {
            const canvas = document.createElement('canvas');
            const ctx = canvas.getContext('2d');
            canvas.height = this.naturalHeight / scaleFactor;
            canvas.width = this.naturalWidth / scaleFactor;
            ctx.scale(1 / scaleFactor, 1 / scaleFactor);
            ctx.drawImage(this, 0, 0);
            URL.revokeObjectURL(file);
            res(canvas.toDataURL("image/jpeg", quality/100));
        };
        img.onerror = rej;
    })
};