Changing the image source using jQuery

Answer 1

Short but exact

$("#d1 img").click(e=> e.target.src= pic[e.target.src.match(pic[0]) ? 1:0] );

let pic=[
  "https://picsum.photos/id/237/40/40", // arbitrary - eg: "img1_on.gif",
  "https://picsum.photos/id/238/40/40", // arbitrary - eg: "img2_on.gif"
];

$("#d1 img").click(e=> e.target.src= pic[e.target.src.match(pic[0]) ? 1:0] );