Math.round(-4.6)和Math.round(-4.5)结果为啥不一样呢？

Question

document.write(Math.round(-4.6) + "
")
document.write(Math.round(-4.5) + "
")
为什么Math.round(-4.6)为-5？？Math.round(-4.5)为-4？？

Answer 1

round是四舍五入
ceil/floor才是取整