js/strict-equality

Dlaczego

== converts both sides before comparing, so "0" == 0, "" == 0 and [] == false are all true. A value read from a form field or a URL is a string, and a loose comparison with a number quietly passes or fails for the wrong reason.

Poprawka

Use === and !==, and convert explicitly where the types differ (Number(input.value) === 3). Keep x == null only where you mean "null or undefined", or write x === null || x === undefined.

Przykłady

// bad
if (params.get('page') == 1) showFirst()
// good
if (Number(params.get('page')) === 1) showFirst()

Źródła

• MDN, Equality comparisons and sameness
• W3Schools, JavaScript Best Practices (use === comparison)
• ESLint, eqeqeq

Przeczytaj w terminalu

npx github:dawidolko/frontend-skills explain js/strict-equality