noEqualsToNull

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JavaScript (and super languages)

Summary

Diagnostic Category: lint/nursery/noEqualsToNull
This rule has an unsafe fix.
The default severity of this rule is error.
Sources:
- Same as no-eq-null

How to configure

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{
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  "linter": {
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    "rules": {
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      "nursery": {
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        "noEqualsToNull": "error"
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      }
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    }
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  }
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}

Description

Require the use of === or !== for comparison with null.

Comparing to null with == or != may have unintended results as the expression evaluates to true when comparing null to undefined.

Examples

Invalid

1
foo == null;

code-block.js:1:5 lint/nursery/noEqualsToNull  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ null comparison with == is disallowed.
  
  > 1 │ foo == null;
      │     ^^
    2 │ 
  
  ℹ Unsafe fix: Use === instead.
  
    1 │ foo·===·null;
      │       +

1
foo != null;

code-block.js:1:5 lint/nursery/noEqualsToNull  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ null comparison with != is disallowed.
  
  > 1 │ foo != null;
      │     ^^
    2 │ 
  
  ℹ Unsafe fix: Use !== instead.
  
    1 │ foo·!==·null;
      │       +

Valid

1
foo === null;

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foo !== null;