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noFunctionAssign (since v1.0.0)

Diagnostic Category: lint/suspicious/noFunctionAssign

Sources:

Disallow reassigning function declarations.

Examples

Section titled Examples

Invalid

Section titled Invalid
function foo() { };
foo = bar;
code-block.js:1:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
  > 1 │ function foo() { };
      │          ^^^
    2 │ foo = bar;
    3 │ 
  
  ℹ Reassigned here.
  
    1 │ function foo() { };
  > 2 │ foo = bar;
      │ ^^^
    3 │ 
  
  ℹ Use a local variable instead.
  

function foo() {
    foo = bar;
 }
code-block.js:1:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
  > 1 │ function foo() {
      │          ^^^
    2 │     foo = bar;
    3 │  }
  
  ℹ Reassigned here.
  
    1 │ function foo() {
  > 2 │     foo = bar;
      │     ^^^
    3 │  }
    4 │ 
  
  ℹ Use a local variable instead.
  

foo = bar;
function foo() { };
code-block.js:2:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
    1 │ foo = bar;
  > 2 │ function foo() { };
      │          ^^^
    3 │ 
  
  ℹ Reassigned here.
  
  > 1 │ foo = bar;
      │ ^^^
    2 │ function foo() { };
    3 │ 
  
  ℹ Reassignment happens here because the function declaration is hoisted.
  
  ℹ Use a local variable instead.
  

[foo] = bar;
function foo() { };
code-block.js:2:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
    1 │ [foo] = bar;
  > 2 │ function foo() { };
      │          ^^^
    3 │ 
  
  ℹ Reassigned here.
  
  > 1 │ [foo] = bar;
      │  ^^^
    2 │ function foo() { };
    3 │ 
  
  ℹ Reassignment happens here because the function declaration is hoisted.
  
  ℹ Use a local variable instead.
  

({ x: foo = 0 } = bar);
function foo() { };
code-block.js:2:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
    1 │ ({ x: foo = 0 } = bar);
  > 2 │ function foo() { };
      │          ^^^
    3 │ 
  
  ℹ Reassigned here.
  
  > 1 │ ({ x: foo = 0 } = bar);
      │       ^^^
    2 │ function foo() { };
    3 │ 
  
  ℹ Reassignment happens here because the function declaration is hoisted.
  
  ℹ Use a local variable instead.
  

function foo() {
    [foo] = bar;
 }
code-block.js:1:10 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
  > 1 │ function foo() {
      │          ^^^
    2 │     [foo] = bar;
    3 │  }
  
  ℹ Reassigned here.
  
    1 │ function foo() {
  > 2 │     [foo] = bar;
      │      ^^^
    3 │  }
    4 │ 
  
  ℹ Use a local variable instead.
  

(function () {
    ({ x: foo = 0 } = bar);
    function foo() { };
 })();
code-block.js:3:14 lint/suspicious/noFunctionAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Do not reassign a function declaration.
  
    1 │ (function () {
    2 │     ({ x: foo = 0 } = bar);
  > 3 │     function foo() { };
      │              ^^^
    4 │  })();
    5 │ 
  
  ℹ Reassigned here.
  
    1 │ (function () {
  > 2 │     ({ x: foo = 0 } = bar);
      │           ^^^
    3 │     function foo() { };
    4 │  })();
  
  ℹ Reassignment happens here because the function declaration is hoisted.
  
  ℹ Use a local variable instead.

Valid

Section titled 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;
}
Section titled Related links