浮点精度向上或向下舍入

Question

Due to conversion between binary and decimal numbers we often see precision errors in JS.

eg.: 137.80 * 100 = 13780.000000000002

Although, is is technically possible that JS will return similar error but with negative precision?

eg.: 137.80 * 100 = 13779.999999999998

Answer 1

Absolutely. For instance, 0.3 / 10000 is 0.000029999999999999997 because 0.3 can't quite be represented, and the closest representation is just slightly lower that the actual value 0.3 . We can see that manifest in the output if we push the limits with the division.