Rule to prefer using `let` to bind names to values
npm install eslint-plugin-prefer-letAn eslint plugin to encourage semantic of usage of let and const.
Things being basically equal, code should speak to humans first, and
computers second. As such, JavaScript codebases should follow the
long-standing conventions set forth by both formal symbolic logic and
the practice of functional programming.
Usage of the const keyword to bind an _intermediate_ value of a
computation places emphasis on the compiler and its role in
ensuring that a _reference_ never changes. By contrast using let in
the same situation reads, in plain English, the programmer's intent to
declare a name value binding.
It is this plugin's opinion that preventing reassignment of let
bindings is better accomplished as a linting rule.
const bindings _are_ allowed at the top-level of a module's scope so
that it can represent a value that is a true, dependency-free constant
such as π, ℯ, etc...
Good:
`` javascript
const PI = 3.14;
function area(radius) {
let r2 = radius * radius;
return PI * r2;
}
`
Bad:
` javascript
function volume(radius) {
const a = area(radius);
return a * radius / 2
}
`
You'll first need to install ESLint:
`
$ npm i eslint --save-dev
Next, install eslint-plugin-prefer-let:
`
$ npm install eslint-plugin-prefer-let --save-dev
Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-prefer-let globally.
Add prefer-let to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:
`json`
{
"plugins": [
"prefer-let"
]
}
Then configure the rules you want to use under the rules section.
`json`
{
"rules": {
"prefer-let/prefer-let": 2
}
}
This plugin may conflict with other plugins or configs that set eslint prefer-const. You can configure the rules to avoid this:
`json``
{
"rules": {
"prefer-let/prefer-let": 2,
"prefer-const": "off"
}
}