ts-r
  • Error
  • Reported by the lexer and parser

TS5076

'{0}' and '{1}' operations cannot be mixed without parentheses.

Two operators like `??` and `||` are mixed without parentheses. Add parentheses to say which runs first.

What it means

?? can't be combined directly with || or && in the same expression. The order of evaluation would be ambiguous to a reader, so the grammar requires parentheses around one side. ts-r's parser reports this as a syntax error.

Example

index.ts
declare const a: string | undefined;
declare const b: boolean;
export const value = a ?? b || "default";
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(3,22): error TS5076: '??' and '||' operations cannot be mixed without parentheses.

Recorded by node scripts/verify-examples.mjs with ts-r built from commit 6deaf01. The example uses the default tsconfig: strict, target: es2022, module: esnext, moduleResolution: bundler.

How to fix

  • Add parentheses around the part that should run first: (a ?? b) || "default" or a ?? (b || "default").