Playing with the ctx in @tmcw's turtle

turtle.js

turtle(function (t) {
  ctx.lineWidth = 3;

  var fns = [];

  [0, 35, 70, 105].forEach(function (a) {
      [0, -90, 180, 90, 180].forEach(function (off) {
        fns.push(function (t) {
          // Originally I just wanted to avoid dense black lines interfering with my ability
          // to read the text as I was typing but then figured why not play with opacity
          // programatically too?
          ctx.strokeStyle = 'rgba(128,128,128,' + Math.abs(Math.sin(t / a)) + ')';

          return (Math.sin((t / a)) * 180) + off;
        });
      });
  });
  
  return fns;
});