Add no-unnecessary-negation rule
#1922
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| # This rule checks if conditions can be simpified | |||
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What about: Use as few negations as possible?
Or: Use as few negations as possible and remove unnecessary Boolean casting.
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| 🔧 _This rule is [auto-fixable](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems)._ | ||
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| <!-- /RULE_NOTICE --> |
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You need to update this per 7d804e3
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| <!-- /RULE_NOTICE --> | ||
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| Dissallow unnecessary negations when using `Boolean` or `!`. |
| ## Fail | ||
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| ```js | ||
| !(a != b); |
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| !(a != b); | |
| !(a !== b); |
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| a == b; | ||
| !a; | ||
| !a; |
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| const MESSAGE_ID = 'no-unnecessary-negation'; | ||
| const messages = { | ||
| [MESSAGE_ID]: 'Expression can be simpified.', |
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What about: Expression can use less negations.?
The problem here is that there are also cases like if (Boolean(a)) { … } that will show this message.
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Nit, but I would suggest Expression can use fewer negations. (fewer instead of less) as the number of negations is an unambiguous integer.
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I just realized that there is no-extra-boolean-cast. |
Resolves #856.
This does not cover swapping for if-statements and ternary expressions, nor does it cover binary algebra optimization.