poweroftwo.js

function powerOfTwo(v){
    return (v & (v - 1)) === 0;
}
function nearPowerOfTwo(v){
    if(v <= 0){return 0;}
    let w = v;
    w = w | (w >> 1);
    w = w | (w >> 2);
    w = w | (w >> 4);
    w = w | (w >> 8);
    w = w | (w >> 16);
    return w + 1;
}

// example with canvas
if(
    object instanceof HTMLImageElement === true &&
    (powerOfTwo(object.naturalWidth) !== true || powerOfTwo(object.naturalHeight) !== true)
){
    let nearWidth = nearPowerOfTwo(object.naturalWidth);
    let nearHeight = nearPowerOfTwo(object.naturalHeight);
    let c = document.createElement('canvas');
    let cx = c.getContext('2d');
    c.width = nearWidth;
    c.height = nearHeight;
    cx.drawImage(object, 0, 0, nearWidth, nearHeight);
    obj = c;
}