eslint-plugin-immutable-bindings

An ESLint plugin that disallows binding reassignments. Should be significantly more effective than prefer-const as it also addresses bindings derived from function arguments.

Why is this better than prefer-const?

1. It can address reassignments of function arguments

   function test (a) {
     a = 2;
   }

   yields:

     11:3   error  Binding reassignment is not allowed for variable 'a'  ib/no-reassign

   This works for destructured arguments too, i.e.

   function test ({a}) {
     a = 2;
   }

   should result with the same error

2. You can force a prefix using {allowPattern: "^mut"}, which is visible everywhere in the code

   let mutItem = 5;
   
   // ...
   // reassign
   mutItem = 8;
   
   // ...
   useCode(mutItem) // very aware of mutable binidng usage sites,
                    // even in code reviews on github

Installation

You can install this plugin using npm:

npm install eslint-plugin-immutable-bindings --save-dev

Usage

Add "immutable-bindings" to your ESLint configuration’s plugins array, then use the rule no-reassign provided by it:

// eslint.config.mjs
import immutableBindings from "eslint-plugin-immutable-bindings";

export default [
  {
    plugins: {
      ib: immutableBindings
    },
    rules: {
      'ib/no-reassign': 'error'
    }
  },
];

Configuration Examples

Allow Variables Starting with “mut”

To allow reassignment for variables whose names start with “mut”:

// eslint.config.mjs
import immutableBindings from "eslint-plugin-immutable-bindings";

export default [
  {
    plugins: {
      ib: immutableBindings
    },
    rules: {
      'ib/no-reassign': ['error', { allowPattern: '^mut' }],
    }
  },
];

License

This project is licensed under the MIT License - see the LICENSE file for details.