javascript运算精度

一个经典的浮点数运算0.1+0.2 == 0.30000000000000004

js在运算的时候会把10进制转化为2进制；

0.1 = 0.0001100110011001...(无限)

0.2 = 0.0011001100110011...(无限)

相加后的二进制0.0100110011001100110011001100110011001100110011001100 就等于上面的数了