noExtraNonNullAssertion
Diagnostic Category: lint/suspicious/noExtraNonNullAssertion
Since: v1.0.0
Sources:
Description
Section titled “Description”Prevents the wrong usage of the non-null assertion operator (!) in TypeScript files.
The
!non-null assertion operator in TypeScript is used to assert that a value’s type does not includenullorundefined. Using the operator any more than once on a single value does nothing.
Examples
Section titled “Examples”Invalid
Section titled “Invalid”const bar = foo!!.bar;code-block.ts:1:13 lint/suspicious/noExtraNonNullAssertion FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Forbidden extra non-null assertion.
> 1 │ const bar = foo!!.bar;
│ ^^^^
2 │
ℹ Safe fix: Remove extra non-null assertion.
1 │ const·bar·=·foo!!.bar;
│ -
function fn(bar?: { n: number }) { return bar!?.n;}code-block.ts:2:10 lint/suspicious/noExtraNonNullAssertion FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Forbidden extra non-null assertion.
1 │ function fn(bar?: { n: number }) {
> 2 │ return bar!?.n;
│ ^^^^
3 │ }
4 │
ℹ Safe fix: Remove extra non-null assertion.
2 │ ··return·bar!?.n;
│ -
function fn(bar?: { n: number }) { return ((bar!))?.();}code-block.ts:2:12 lint/suspicious/noExtraNonNullAssertion FIXABLE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Forbidden extra non-null assertion.
1 │ function fn(bar?: { n: number }) {
> 2 │ return ((bar!))?.();
│ ^^^^
3 │ }
4 │
ℹ Safe fix: Remove extra non-null assertion.
2 │ ··return·((bar!))?.();
│ -
const bar = foo!.bar;
obj?.string!.trim();
function fn(key: string | null) { const obj = {}; return obj?.[key!];}How to configure
Section titled “How to configure”{ "linter": { "rules": { "suspicious": { "noExtraNonNullAssertion": "error" } } }}