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noUnusedVariables (since v0.9.0)

This rule is recommended by Rome.

Disallow unused variables.

Examples

Invalid

const a = 4;
error[js/noUnusedVariables]: This variable is unused.
   js/noUnusedVariables.js:1:7
  
1  const a = 4;
         ^

Suggested fix: Remove this variable.
    | @@ -1 +1 @@
0   | - const a = 4;
  0 | + 

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

let a = 4;
error[js/noUnusedVariables]: This variable is unused.
   js/noUnusedVariables.js:1:5
  
1  let a = 4;
       ^

Suggested fix: Remove this variable.
    | @@ -1 +1 @@
0   | - let a = 4;
  0 | + 

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

function foo() {
};
error[js/noUnusedVariables]: This function is unused.
   js/noUnusedVariables.js:1:10
  
1  function foo() {
            ^^^

Suggested fix: Remove this function.
    | @@ -1,2 +1 @@
0   | - function foo() {
1   | - };
  0 | + ;

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

function foo(myVar) {
console.log('foo');
}
foo();
error[js/noUnusedVariables]: This parameter is unused.
   js/noUnusedVariables.js:1:14
  
1  function foo(myVar) {
                ^^^^^

Suggested fix: Remove this parameter.
    | @@ -1,4 +1,4 @@
0   | - function foo(myVar) {
  0 | + function foo() {
1 1 |       console.log('foo');
2 2 |   }
3 3 |   foo();

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

const foo = () => {
};
error[js/noUnusedVariables]: This variable is unused.
   js/noUnusedVariables.js:1:7
  
1  const foo = () => {
         ^^^

Suggested fix: Remove this variable.
    | @@ -1,2 +1 @@
0   | - const foo = () => {
1   | - };
  0 | + 

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

function foo() {
foo();
}
error[js/noUnusedVariables]: This function is unused.
   js/noUnusedVariables.js:1:10
  
1  function foo() {
            ^^^

Suggested fix: Remove this function.
    | @@ -1,3 +1 @@
0   | - function foo() {
1   | -     foo();
2   | - }
  0 | + 

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

const foo = () => {
foo();
console.log(this);
};
error[js/noUnusedVariables]: This variable is unused.
   js/noUnusedVariables.js:1:7
  
1  const foo = () => {
         ^^^

Suggested fix: Remove this variable.
    | @@ -1,4 +1 @@
0   | - const foo = () => {
1   | -     foo();
2   | -     console.log(this);
3   | - };
  0 | + 

=  note: Unused variables usually are result of incomplete refactoring, typos and other source of bugs.

Valid

function foo(b) {
console.log(b)
};
foo();