eslint-plugin-object-merge

Rules to enforce side effect-free use of Lodash.merge() and similar object merge methods

Limitations

Currently only validates the case where merge() is imported via an ES6 import like so:

• import { merge } from 'lodash';
• import { merge } from 'lodash/merge';

Unsupported cases:

• import lodash from 'lodash'; /*...*/ lodash.merge(); // Default import
• const merge = require('lodash/merge'); // CommonJS

Installation

You'll first need to install ESLint:

$ npm i eslint --save-dev

Next, install eslint-plugin-object-merge:

$ npm install eslint-plugin-object-merge --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-object-merge globally.

Usage

Add object-merge to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

{
    "plugins": [
        "object-merge"
    ]
}

Then configure the rules you want to use under the rules section.

{
    "rules": {
        "object-merge/rule-name": 2
    }
}

Supported Rules

no-side-effects

Detect possibly unsafe use of Lodash.merge (or similar functions) that mutate their first object argument

Lodash's merge() function, like the native Object.assign(), mutates that first argument passed to it. This is often undesired behavior as it can cause unexpected mutations to objects that are used outside the immediate scope. This rule can be used to catch potentially unsafe cases where the first argument will be mutated.

(See tests for full list of valid/invalid cases.)

{
    "rules": {
        "object-merge/no-side-effects": [2, {
          // Names of function calls to validate for possible side effects (optional, default shown below)
          "functionNames": ["merge"],

          // Names of packages from which functions must be imported in order to be validated (optional, default shown below)
          "packageNames": ["lodash", "lodash/merge"]
        }]
    }
}