canvas认识

<canvas id="canvas" width="640" height="360"></canvas>

<script>
//    获取context对象
    var canvas = document.getElementById(‘canvas‘);
    if(canvas.getContext) {
        var context = canvas.getContext(‘2d‘);
//        设置颜色
        context.fillStyle = ‘rgb(255,0,0)‘;
//        从坐标（20,30）开始，画一个64x36大小的矩形
        context.fillRect(20,30,64,36);
    }
</script>