noFunctionAssign (since v0.7.0)

This rule is recommended by Rome.

Disallow reassigning function declarations.

Examples

Invalid

function foo() { };
foo = bar;

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:1:10
  │
1 │ function foo() { };
  │          ^^^
2 │ foo = bar;
  │ --- Reassigned here.

=  note: Use a local variable instead.

function foo() {
    foo = bar;
 }

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:1:10
  │
1 │ function foo() {
  │          ^^^
2 │     foo = bar;
  │     --- Reassigned here.

=  note: Use a local variable instead.

foo = bar;
function foo() { };

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:2:10
  │
1 │ foo = bar;
  │ --- Reassigned here.
2 │ function foo() { };
  │          ^^^

=  note: Reassignment happens here because the function declaration is hoisted.
=  note: Use a local variable instead.

[foo] = bar;
function foo() { };

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:2:10
  │
1 │ [foo] = bar;
  │  --- Reassigned here.
2 │ function foo() { };
  │          ^^^

=  note: Reassignment happens here because the function declaration is hoisted.
=  note: Use a local variable instead.

({ x: foo = 0 } = bar);
function foo() { };

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:2:10
  │
1 │ ({ x: foo = 0 } = bar);
  │       --- Reassigned here.
2 │ function foo() { };
  │          ^^^

=  note: Reassignment happens here because the function declaration is hoisted.
=  note: Use a local variable instead.

function foo() {
    [foo] = bar;
 }

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:1:10
  │
1 │ function foo() {
  │          ^^^
2 │     [foo] = bar;
  │      --- Reassigned here.

=  note: Use a local variable instead.

(function () {
    ({ x: foo = 0 } = bar);
    function foo() { };
 })();

error[js/noFunctionAssign]: Do not reassign a function declaration.
  ┌─ js/noFunctionAssign.js:3:14
  │
2 │     ({ x: foo = 0 } = bar);
  │           --- Reassigned here.
3 │     function foo() { };
  │              ^^^

=  note: Reassignment happens here because the function declaration is hoisted.
=  note: Use a local variable instead.

Valid

function foo() {
    var foo = bar;
 }

function foo(foo) {
    foo = bar;
 }

function foo() {
    var foo;
    foo = bar;
 }

var foo = () => {};
foo = bar;

var foo = function() {};
foo = bar;

var foo = function() {
    foo = bar;
 };

import bar from 'bar';
function foo() {
    var foo = bar;
}