How to get a pixel's x,y coordinate color from an image?

Question

Is there any way to check if a selected(x,y) point of a PNG image is transparent?

Answer 1

With : i << 2

const data = context.getImageData(x, y, width, height).data;
const pixels = [];

for (let i = 0, dx = 0; dx < data.length; i++, dx = i << 2) {
    if (data[dx+3] <= 8)
        console.log("transparent x= " + i);
}