HTML canvas globalCompositeOperation Property

// Accessing the element
let c = document.getElementById("myCanvas");

let ctx = c.getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(25, 25, 50, 50);
ctx.globalCompositeOperation = "source-over";
ctx.fillStyle = "blue";
ctx.fillRect(50, 50, 50, 50);
ctx.fillStyle = "green";
ctx.fillRect(75, 75, 50, 50);

source-over

context.globalCompositeOperation="source-in";