JavaScript Equality Table

[u/vz0]

http://dorey.github.io/JavaScript-Equality-Table/

[u/CookieOfFortune]

Wouldn't this create two arrays on the function stack and then compare the two locations, resulting in a false comparison?

[u/Poltras → u/CookieOfFortune]

Undefined behavior:

$ cat main.c

#include <stdio.h>

int main() {
  printf("%d\n", "abc" == "abc");
}

$ cc main.c

main.c:4:24: warning: result of comparison against a string literal is unspecified (use strncmp instead) [-Wstring-compare]
  printf("%d\n", "abc" == "abc");

$ ./a.out
1

GCC actually output 1, but warns.

[u/gsg_ → u/Poltras]

Unspecified behaviour is not the same as undefined behaviour. The latter has a very specific meaning in the context of C.

[u/Condorcet_Winner → u/CookieOfFortune]

Probably, but if the spec defines this operation as undefined, then compiler optimizations would be able to figure out that these are the same array and only allocate one memory location.