@putout/plugin-logical-expressions [![NPM version][NPMIMGURL]][NPMURL]

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> The logical NOT (!) operator takes truth to falsity and vice versa.
>
> (c) MDN

🐊Putout plugin adds ability to simplify logical expressions containing
comparisons which will always evaluate to true or false since it's likely indications of programmer error.

Complements @putout/plugin-apply-comparison-order.

Install

``
npm i @putout/plugin-logical-expressions -D
`

Rules

- ✅ convert-bitwise-to-logical;
- ✅ remove-boolean;
- ✅ remove-duplicates;
- ✅ simplify;

Config

`json
{
"rules": {
"logical-expressions/simplify": "on",
"logical-expressions/remove-boolean": "on",
"logical-expressions/remove-duplicates": "on",
"logical-expressions/convert-bitwise-to-logical": "on"
}
}
`

simplify

$3

`js
const is = !(options && !options.bidirectional);

if (!left.type === 'UnaryExpression') {}

const oneOf = a || a;
const same = a === a;

a() && b;
`

$3

`js
const is = !options || options.bidirectional;

if (left.type !== 'UnaryExpression') {}

const oneOf = a;
const same = true;

a();
`

The rule also simplify duplication use:

`diff
-if (a && b || a && c) {
+if (a && (b || c)) {
}
`

Wrong cases with instanceof:

`diff
-!a instanceof b;
-a instanceof !b;
-!a instanceof !b;
+!(a instanceof b);
`

Wrong cases with in:

`diff
-!a in b;
-a in !b;
+!(a in b);
`

In case of duplicates:

`diff
-a && b && a
+a && b
`

remove-boolean

> A boolean is a logical data type that can have only the values true or false.
>
> (c) MDN

$3

`js
const t = true && false;
`

$3

`js
const t = false;
`

remove-duplicates

$3

`js
const t = a && b && a;
`

$3

`js
const t = a && b;
`

convert-bitwise-to-logical

> The bitwise OR operator (|) returns a 1 in each bit position for which the corresponding bits of either or both operands are 1s.
>
> The operands are converted to 32-bit integers and expressed by a series of bits (zeroes and ones).
>
> (c) MDN

Convert bitwise to logical operator, when one of operands is not a number, since mostly likely it is an error.

$3

`js
a | !b;

if (!(a !== b))
fn();
`

$3

`js
a || !b;

if (a === b)
fn();
`

Comparison

Linter | Rule | Fix
--------|-------|------------|
🐊 Putout| logical-expressions| ✅
⏣ ESLint | no-constant-binary-expression` | ❌

License

MIT