ESLintRequire IIFEs to be Wrapped (wrap-iife)
Require immediate function invocation to be wrapped in parentheses.
var x = function () { return { y: 1 };}();
Rule Details
Since function statements cannot be immediately invoked, and function expressions can be, a common technique to create an immediately-invoked function expression is to simply wrap a function statement in parentheses. The opening parentheses causes the contained function to be parsed as an expression, rather than a declaration.
Options
The rule takes one option which can enforce a consistent wrapping style. The default is outside.
"wrap-iife": [2, "outside"]
This configures the rule to enforce wrapping always the call expression.
"wrap-iife": [2, "inside"]
This configures the rule to enforce wrapping always the function expression.
"wrap-iife": [2, "any"]
This allows any wrapping style.
The following patterns are considered problems:
/*eslint wrap-iife: 2*/
var x = function () { return { y: 1 };}(); /*error Wrap an immediate function invocation in parentheses.*/
/*eslint wrap-iife: [2, "outside"]*/
var x = (function () { return { y: 1 };})(); /*error Move the invocation into the parens that contain the function.*/
/*eslint wrap-iife: [2, "inside"]*/
var x = (function () { return { y: 1 };}()); /*error Wrap only the function expression in parens.*/
The following patterns are not considered problems:
/*eslint wrap-iife: [2, "inside"]*/
var x = (function () { return { y: 1 };})();
/*eslint wrap-iife: [2, "outside"]*/
var x = (function () { return { y: 1 };}());
Version
This rule was introduced in ESLint 0.0.9.