计算中无用的小数

Question

Might somebody already faced with calculation issue like in snippet below. First console command shows useless digits after calculation 10.1 +20.1 should be 30.2 but calculated as 30.200000000000003. and second one 10.2 + 20.2=30.4 is correct. There can be a lot of such decimal pairings which creates additional decimals in summ. Why does it happends and hove to avoid it?

 console.log(10.1 + 20.1); console.log(10.2 + 20.2);

Answer 1

This looks like a duplicate of How to deal with floating point number precision in JavaScript? .

You can use.toFixed(2) to always get a number with only 2 decimals. https://www.w3schools.com/jsref/jsref_tofixed.asp

More info: https://www.w3schools.com/js/js_numbers.asp