Any order of explanation means something is often discussed before the reason for doing it is clear. In this section, I will show how certain variables are set that will be shown in use later on. The general plan is to extract the window dimensions to set variables for the canvas and the video clip that will be referenced in the coding for drawing the video and the mask.
The Document Object Model (DOM) provides information about the window in which the HTML document is displayed by the browser. In particular, the attributes
window.innerHeight indicate the usable dimensions of the window. My code will use these values when it sets up the ...