// Drop a bunch of needles
var x1, y1, theta, x2, y2;
for (var i = 0; i < numberToDrop; i++) {
    // Drop a new needle
    x1 = (Math.random() * (width - 2 * needleLength)) + needleLength;
    y1 = (Math.random() * (height - 2 * needleLength)) + needleLength;
    theta = Math.random() * 2 * Math.PI;

    x2 = x1 + needleLength * Math.cos(theta);
    y2 = y1 + needleLength * Math.sin(theta);

    // Check if it crosses a line
    // Yes, this isn't the best way to do this
    var crossesLine = false;
    for (var x = needleLength / 2; x <= canvas.width; x += needleLength) {
        if ((x1 <= x && x <= x2) || (x2 <= x && x <= x1))
            crossesLine = true;
    }

    // Record the toss
    tossed += 1;
    if (crossesLine) crossed += 1;
}

console.log("pi ~ " + (2 * tossed / crossed));