Some features that every JavaScript developer should know in 2025

… Swapping variables: Only do this if you don't care about performance (the advice is written like using the array swap hack is categorically better). ... Now then the question is whether it is optimised so. And that’s the problem with categoric statements in a language like JavaScript: if you make arguments about fine performance things, they’re prone to change, because JavaScript performance is a teetering stack of flaming plates liable to come crashing down if you poke it in the wrong direction, which changes from moment to moment as the pile sways.