prefer-array-some.md

Prefer .some(…) over .filter(…).length check and .{find,findLast,findIndex,findLastIndex}(…)

💼 This rule is enabled in the ✅ recommended config.

🔧💡 This rule is automatically fixable by the --fix CLI option and manually fixable by editor suggestions.

Prefer using Array#some over:

• Non-zero length check on the result of Array#filter().

We only check .filter().length > 0 and .filter().length !== 0. These two non-zero length check styles are allowed in unicorn/explicit-length-check rule. It is recommended to use them together.

• Using Array#find() or Array#findLast() to ensure at least one element in the array passes a given check.

• Comparing the result of Array#find() or Array#findLast() with undefined.

• Using Array#findIndex() or Array#findLastIndex() to ensure at least one element in the array passes a given check.

This rule is fixable for .filter(…).length checks and .{findIndex,findLastIndex}(…).

This rule provides a suggestion for .{find,findLast}(…).

Fail

const hasUnicorn = array.filter(element => isUnicorn(element)).length > 0;

const hasUnicorn = array.filter(element => isUnicorn(element)).length !== 0;

const hasUnicorn = array.filter(element => isUnicorn(element)).length >= 1;

if (array.find(element => isUnicorn(element))) {
	// …
}

const foo = array.find(element => isUnicorn(element)) ? bar : baz;

const hasUnicorn = array.find(element => isUnicorn(element)) !== undefined;

const hasUnicorn = array.find(element => isUnicorn(element)) != null;

if (array.find(element => isUnicorn(element))) {
	// …
}

const foo = array.findLast(element => isUnicorn(element)) ? bar : baz;

const hasUnicorn = array.findLast(element => isUnicorn(element)) !== undefined;

const hasUnicorn = array.findLast(element => isUnicorn(element)) != null;

const hasUnicorn = array.findIndex(element => isUnicorn(element)) !== -1;

const hasUnicorn = array.findLastIndex(element => isUnicorn(element)) !== -1;

<template>
	<div v-if="array.find(element => isUnicorn(element))">Vue</div>
</template>

<template>
	<div v-if="array.findLast(element => isUnicorn(element))">Vue</div>
</template>

<template>
	<div v-if="array.filter(element => isUnicorn(element)).length > 0">Vue</div>
</template>

Pass

const hasUnicorn = array.some(element => isUnicorn(element));

if (array.some(element => isUnicorn(element))) {
	// …
}

const foo = array.find(element => isUnicorn(element)) || bar;

const foo = array.findLast(element => isUnicorn(element)) || bar;

<template>
	<div v-if="array.some(element => isUnicorn(element))">Vue</div>
</template>