Simplest example of a Waterbear script (for Javascript canvas)

random_circles.js

local.count_1 = 0;
(function() {
    setInterval(function() {
        local.count_1++;
        var point_2 = {
            x: randint(0, global.stage_width),
            y: randint(0, global.stage_height)
        };
        var radius_2 = randint(20, 50);
        var color_2 = "rgb(" + randint(0, 255) + "," + randint(0, 255) + "," + randint(0, 255) + ")";
        local.ctx.save();
        local.ctx.fillStyle = color_2;
        local.ctx.beginPath();
        local.ctx.arc(point_2.x, point_2.y, radius_2, 0, Math.PI * 2, true);
        local.ctx.closePath();
        local.ctx.fill();
        local.ctx.restore();
    }, 1000 / 30)
})();

random_circles.json

{"title":"","description":"","date":1353822097063,"scripts":{"waterbearVersion":"1.0","plugins":["javascript","canvas","sprite"],"workspace":"default","blocks":[{"signature":"eventhandler: repeat [number] times a second","blocktype":"eventhandler","id":1,"values":[{"type":"number","value":30}],"contained":[{"signature":"step: fill circle at point [point] with radius [number] and color [color]","blocktype":"step","id":2,"values":[{"type":"point","value":{"signature":"expression: random point","blocktype":"expression","id":3}},{"type":"number","value":{"signature":"expression: pick random [number] to [number]","blocktype":"expression","id":4,"values":[{"type":"number","value":20},{"type":"number","value":50}]}},{"type":"color","value":{"signature":"expression: random color","blocktype":"expression","id":5}}]}]}]}}