The code examples page is a thing of beauty and simplicity, bravo! https://svelte.dev/examples#hello-world
export function safe_not_equal(a, b) { return a != a ? b == b : a !== b || ((a && typeof a === 'object') || typeof a === 'function'); }
Why is it possible for a != a to not always be false and b == b to not always be true? How did Javascript defeat the most immutable rule of basic logic discovered by Aristotle 2000 years ago?
Unsafe equality: "1" == 1 is true (string and float, https://dev.to/mkrl/javascript-quirks-in-one-image-from-the-...).
Yet, like with C, you learn the different ways you can shoot yourself in the foot over time and avoid them. In 10 years I've never written a safe_not_equals function, although explicit object/null checks are a thing, but it wouldn't surprise me if libraries used by millions that may end up in Internet Explorer go that extra step. Each language has it's particular use-case, JS happens to be the language of web development.