<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>