- box-sizing
- flash screen when redraw canvas
reason: execute order
// drwa pic
draw()
// clear pic
clearRect()
draw()
// redraw pic
draw()
solution:
// drwa pic
draw()
// clear pic
clearRect()
// redraw pic
draw()
- unload
頁面卸載后崔列，開發(fā)工具存在不走onload的問題门怪，但是真機(jī)不存在
