eslint-plugin-prefer-number-isnan

Eslint plugin to disallow checking for NaN by self comparison

In ES5 you can check for NaN values by using the Number.isNaN method or you can compare a variable to itself value !== value. The latter method is equivalent to the former but much less readable.

Examples of incorrect code for rule prefer-number-isnan

const fooIsNaN = foo !== foo;

const fooIsNotNaN = foo === foo;

const alwaysFalse = NaN == NaN;

Examples of correct code for rule prefer-number-isnan

const fooIsNaN = Number.isNaN(foo);

const fooIsNotNaN = !Number.isNaN(foo);

const alwaysFalse = !Number.isNaN(NaN);

Code can be automatically --fixed to use Number.isNaN. Comments inside the comparison expression will disable automatic --fix for that violation.

This rule will not check for degenerate comparisons like foo == NaN that are usually defects. There already is use-isnan for that.