noUselessThisAlias (JavaScript)

Language JavaScript (and super languages)

Summary

• Rule available since: v1.0.0
• Diagnostic Category: lint/complexity/noUselessThisAlias
• This rule is recommended, meaning it is enabled by default.
• This rule has a safe fix.
• The default severity of this rule is information.
• Sources:
  • Inspired from @typescript-eslint/no-this-alias

How to configure

biome.json

{
  "linter": {
    "rules": {
      "complexity": {
        "noUselessThisAlias": "error"
      }
    }
  }
}

Description

Disallow useless this aliasing.

Arrow functions inherits this from their enclosing scope; this makes this aliasing useless in this situation.

Examples

Invalid

class A {
    method() {
        const self = this;
        return () => {
            return self;
        }
    }
}

code-block.js:3:15 lint/complexity/noUselessThisAlias  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ This aliasing of this is unnecessary.
  
    1 │ class A {
    2 │     method() {
  > 3 │         const self = this;
      │               ^^^^^^^^^^^
    4 │         return () => {
    5 │             return self;
  
  ℹ Arrow functions inherits `this` from their enclosing scope.
  
  ℹ Safe fix: Use this instead of an alias.
  
    1 1 │   class A {
    2 2 │       method() {
    3   │ - ········const·self·=·this;
    4 3 │           return () => {
    5   │ - ············return·self;
      4 │ + ············return·this;
    6 5 │           }
    7 6 │       }
  

Valid

class A {
    method() {
        const self = this;
        return function() {
            this.g();
            return self;
        }
    }
}

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