noUselessUndefined
Summary
Section titled Summary- Diagnostic Category:
lint/nursery/noUselessUndefined - This rule has a safe fix.
- The default severity of this rule is information.
- Sources:
- Same as
unicorn/no-useless-undefined
- Same as
Description
Section titled DescriptionDisallow the use of useless undefined.
undefined is the default value for new variables, parameters, return statements, etc., so specifying it doesn’t make any difference.
Examples
Section titled ExamplesInvalid
Section titled Invalidlet foo = undefined;code-block.js:1:11 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
> 1 │ let foo = undefined;
│ ^^^^^^^^^
2 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
1 │ let·foo·=·undefined;
│ -----------
const {foo = undefined} = bar;code-block.js:1:14 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
> 1 │ const {foo = undefined} = bar;
│ ^^^^^^^^^
2 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
1 │ const·{foo·=·undefined}·=·bar;
│ -----------
const noop = () => undefined;code-block.js:1:20 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
> 1 │ const noop = () => undefined;
│ ^^^^^^^^^
2 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
1 │ - const·noop·=·()·=>·undefined;
1 │ + const·noop·=·()·=>·{};
2 2 │
function foo() { return undefined;}code-block.js:2:11 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
1 │ function foo() {
> 2 │ return undefined;
│ ^^^^^^^^^
3 │ }
4 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
2 │ ···return·undefined;
│ ---------
function* foo() { yield undefined;}code-block.js:2:9 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
1 │ function* foo() {
> 2 │ yield undefined;
│ ^^^^^^^^^
3 │ }
4 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
2 │ ··yield·undefined;
│ ---------
function foo(bar = undefined) {}code-block.js:1:20 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
> 1 │ function foo(bar = undefined) {}
│ ^^^^^^^^^
2 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
1 │ function·foo(bar·=·undefined)·{}
│ -----------
function foo({bar = undefined}) {}code-block.js:1:21 lint/nursery/noUselessUndefined FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
ℹ Don’t use unnecessary undefined.
> 1 │ function foo({bar = undefined}) {}
│ ^^^^^^^^^
2 │
ℹ undefined is the default value for new variables, parameters, return statements, etc… so specifying it doesn’t make any difference.
ℹ Safe fix: Remove the undefined.
1 │ function·foo({bar·=·undefined})·{}
│ -----------
Valid
Section titled Validlet foo;const {foo} = bar;function foo() { return;}function* foo() { yield;}function foo(bar) {}function foo({bar}) {}foo();How to configure
Section titled How to configure{ "linter": { "rules": { "nursery": { "noUselessUndefined": "error" } } }}