Avoid variable or function declaration in nested blocks
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ID: javascript-best-practices/no-inner-declarations
Language: JavaScript
Severity: Warning
Category: Error Prone
Description
Function declarations in JavaScript are generally not block scoped. This rule prevents function declarations inside nested blocks like if statements. Move your declarations to the root of your program, body, or class.
Non-Compliant Code Examples
if (test) { function doSomething() { } }
if (foo) var a;
if (foo) /* some comments */ var a;
if (foo){ function f(){ if(bar){ var a; } } }
if (foo) function f(){ if(bar) var a; }
if (foo) { var fn = function(){} }
if (foo) function f(){}
function bar() { if (foo) var a; }
if (foo){ var a; }
class C { method() { if(test) { var foo; } } }
class C { static { if (test) { function foo() {} } } }
class C { static { if (test) { var foo; } } }
class C { static { if (test) { if (anotherTest) { var foo; } } } }
Compliant Code Examples
function doSomething() { }
function doSomething() { function somethingElse() { } }
(function() { function doSomething() { } }());
function decl() { var fn = function expr() { }; }
function decl(arg) { var fn; if (arg) { fn = function() { }; } }
var x = {doSomething() {function doSomethingElse() {}}}
function decl(arg) { var fn; if (arg) { fn = function expr() { }; } }
function decl(arg) { var fn; if (arg) { fn = function expr() { }; } }
if (test) { let x = 1; }
if (test) { const x = 1; }
function doSomething() { while (test) { var foo; } }
var foo;
var foo = 42;
function doSomething() { var foo; }
(function() { var foo; }());
foo(() => { function bar() { } });
var fn = () => {var foo;}
var x = {doSomething() {var foo;}}
export var foo;
export function bar() {}
export default function baz() {}
exports.foo = () => {}
exports.foo = function(){}
module.exports = function foo(){}
class C { method() { function foo() {} } }
class C { method() { var x; } }
class C { static { function foo() {} } }
class C { static { var x; } }
