Prevents IIFE usage
An eslint plugin to prevent immediately-invoked function
expression (IIFE) usage in your code.
``shell`
npm install --save-dev eslint-plugin-no-iife
In your .eslintrc (or wherever your eslint configuration lives):
`json`
{
"plugins": [
"no-iife"
],
"rules": {
"no-iife/no-iife": "error"
}
}
This rule prevents all immediately-invoked function expressions.
Immediately-invoked function expressions are a messy remnant of early
Javascript, and their use today only serves to decrease readability. They can
and should be entirely replaced with modern syntax.
Historically, the IIFE had two main advantages. First, it served as a shorthand
for calling a function which was just defined. While this pattern can lead to
convoluted code, there are a handful of legitimate reasons to call code
immediately after definition, such as factory functions. However, it is much
more human-readable to define a function and then call it in the next statement.
Compare this IIFE:
`javascript`
const x = (function() {
return function() {
foo();
}
})();
With this version:
`javascript`
const y = function() {
return function() {
foo();
}
};
const x = y();
The other use-case for IIFEs was much more practical; imposing a limited scope.
The problem arises from var, which hoists variables to the top of the functionvar
scope. In a top-level script, the function scope is global, making all the
variables global. And since variables can be reassigned with another usevar
of , it's all too easy to override existing globals. Besides, having so
many global variables makes debugging far more difficult.
IIFEs solve this problem by wrapping a script in an anonymous function, limiting
the scope to just one page (or less). This was a savior for many common
problems, but at the cost of being messy and confusing.
In modern Javascript, however, var is rarely used, and so the problem ofconst
global variable pollution has entirely disappeared. By using and let`,
there is simply no need for IIFEs anymore.
Copyright (c) 2019 Jade Michael Thornton
Permission to use, copy, modify, and/or distribute this software for any purpose
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