Apply a masked circle on element.

seeThroughMain.js

// Main process
export const createSeeThroughWindow = () => {
    const w = new BrowserWindow({ transparent: true });
    w.setIgnoreMouseEvents(true);
};

seeThroughRenderer.js

// Renderer process
const mask_radius = 200;
export const moveSeeThrough = ({x, y}) => {
    const $body = document.body;
    const newX = $body.scrollLeft + x;
    const newY = $body.scrollTop + y;
    
    $body.setAttribute('style', `-webkit-mask-image: radial-gradient(
        ${mask_radius}px at ${newX}px ${newY}px ,
        rgba(0, 0, 0, 0) 0%,
        rgba(0, 0, 0, 0) 99%,
        rgba(0, 0, 0, 1) 100%
    );`);
};