Incremental random matrix

inc_rand_mat.js

function draw_matrix(context, matrix, startx, starty, cellsize)
{
    var x = startx;
    var y = starty;
    var colors = ['yellow', 'red'];

        
    for (var i=0; i<matrix.length; ++i)	{
	line = matrix[i];
	for (var j=0; j<line.length; ++j) {

	    context.beginPath();
	    
	    context.rect(x, y, cellsize, cellsize);
	    context.fillStyle = colors[line[j]];
	    context.fill();
	    x += cellsize;
	    
	}

	x = startx;
	y += cellsize;
    }
}

function random_matrix(width, length)
{
    matrix = [];

    for (var i=0; i<length; ++i) {
	line = [];

	for (var j=0; j<width; ++j) 
	    line.push(Math.floor(Math.random()*2))

	matrix.push(line);
    }

    return matrix;
}

window.onload = function () {
    var canvas = document.getElementById('myCanvas');
    var context = canvas.getContext('2d');

    for (var n=0; n<10; ++n) {
	context.clearRect(0,0,canvas.width, canvas.height);
	setTimeout(draw_matrix(context, random_matrix(3, 3), 50, 50, 20), 1000);

    }

};