> 结论写在头
var oC = document.getElementById('c1');
var oGC = oC.getContext('2d');
oGC.strokeRect(50,50,100,100);//默认绘制黑色一像素的线var oC = document.getElementById('c1'var oC = document.getElementById('c1');
var oGC = oC.getContext('2d');
oGC.strokeRect(50,50,100,100);//默认绘制黑色一像素的线var oC = document.getElementById('c1'