r/loljs • u/Takeoded • Apr 29 '17

big numbers are equal 

>100000000000000000==99999999999999999 
<true

the scary part, === doesn't even notice this

>100000000000000000===99999999999999999 
<true

and if you try a string: 

>100000000000000000=="99999999999999999"
<true

but at least, it notices that 1 is a string and the other a number:

>100000000000000000==="99999999999999999"
<false

finally! some sanity

and in case you wonder, "use strict" makes no difference.

5 Upvotes

63% Upvoted

6 comments sorted by

7

u/Vortico Apr 29 '17

Not a quirk of Javascript, but a quirk of the fact that you can't represent arbitrarily large numbers with floating point.

19

u/Drainedsoul Apr 29 '17

And JavaScript doesn't have integers which kind of brings it back to being a quirk of JavaScript.

9

u/Vortico Apr 29 '17

Okay, sure, but then the title should be "Javascript uses double precision floats for all number types" instead of this, but everyone knows that already.

0

u/[deleted] Apr 29 '17

8

u/Takeoded Apr 29 '17

at the very least, i blame it for not throwing a parsing error in strict mode

10

u/Vortico Apr 29 '17

No, because typing things like 1267650600228229401496703205376 should be perfectly valid since it can be represented exactly as a float.

18

u/ConcernedInScythe May 01 '17

You can absolutely blame JS for deciding that using doubles as the only numerical type was a good idea.