[elcaro]

The closest thing these days is probably p5js (Processing in JS).

    function setup() {
      createCanvas(640, 480)
    }

    function draw() {
      background(0, 100, 200)
      strokeWeight(100)
      stroke(200, 200, 0)
      line(0, 0, 640, 480)
    }

There's an online editor so pre-teens (or indeed post-teens) can get started right away (https://editor.p5js.org) but I'll admit there's still quite a hurdle if you want to host yourself, or run offline.