blocks for loop and random number lesson

blocks.html

<canvas id='myCanvas' width="400" height="400"></canvas>
<script>
    var ctx = document.getElementById('myCanvas').getContext('2d');

    var colors = [
        'red',
        'blue',
        'green',
        'yellow',
        'purple']
    
    function drawBlock(){
        var blocks = [];
        for (var i=0; i < 100; i++){
            colorIndex = Math.floor(Math.random()  * colors.length);
            blockColor = colors[colorIndex];
            blockX = Math.floor(Math.random() * 400);
            blockY = Math.floor(Math.random()  * 400);
            ctx.fillStyle = blockColor;
            ctx.fillRect(blockX, blockY, 6, 6);
        }
        setTimeout(drawBlock, 2000);
    }

    drawBlock();

</script>