eslint-plugin-classes-bind-methods

Expect classes to bind instance methods in the constructor

Installation

You'll first need to install ESLint:

$ npm i eslint --save-dev

Next, install eslint-plugin-classes-bind-methods:

$ npm install eslint-plugin-classes-bind-methods --save-dev

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

Purpose

Instance methods which call out to other instance methods or variables using the this keyword must have been bound to this before the call, otherwise a TypeError will occur.

Rule Details

Reduce the occurance of TypeErrors caused by dereferencing an undefined this inside an instance method.

Usage

Add classes-bind-methods to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

{
    "plugins": [
        "classes-bind-methods"
    ]
}

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

{
    "rules": {
        "classes-bind-methods/classes-bind-methods": "error"
    }
}

Options

Ignoring Specific Methods

classes-bind-methods can be configured to ignore every occurance of a given method name in classes throughout your project. For example, to not enforce binding for methods named foo, extend your .eslintrc file to include the following:

// .eslintrc.json (or similar)
{
  ...
  "rules": {
    "classes-bind-methods/classes-bind-methods":["error", {
      ...
      "ignoreMethodNames": ["foo"],
      ...
    }],
  }
  ...
}

Subclasses

The rule can also be configured to only consider or ignore classes which extend one of a specified set classes. For example, to only consider classes which extend foo, modify your .eslintrc file to include the following:

// .eslintrc.json (or similar)
{
  ...
  "rules": {
    "classes-bind-methods/classes-bind-methods":["error", {
      ...
      "onlySubclasses": ["foo"],
      ...
    }],
  }
  ...
}

To consider every class except those in a specific set (like foo and bar), modify your .eslintrc file to include the following:

// .eslintrc.json (or similar)
{
  ...
  "rules": {
    "classes-bind-methods/classes-bind-methods":["error", {
      ...
      "ignoreSubclasses": ["foo", "bar"],
      ...
    }],
  }
  ...
}

Ignoring or including only specific file extensions

To only apply this rule (or conversely, not apply this rule) to files with a specific file extension (e.g. .jsx files), modify your .eslintrc file to include the following:

// .eslintrc.json (or similar)
{
  ...
  "rules": {
    "classes-bind-methods/classes-bind-methods":["error", {
      ...
      "ignoreFileExtensions": ["js","foo"],
      ... or ...
      "onlyFileExtensions": ["jsx","bar"],
      ...
    }],
  }
  ...
}

React

If you have correctly configured eslint with React, standard Component lifecycle methods will automatically be ignored. If you're getting these errors and find it obnoxious to bind render in the constructor, make sure that you've included react in your eslint settings, as follows:

// .eslintrc.json (or similar)
{
  ...
  "settings": {
    "react": {
      /* Honestly you can put whatever you want here and this rule will behave no differently */
    }
  }
  ...
}

Supported Rules

• classes-bind-methods