E0255: missing parentheses around parameter; TypeScript type annotation requires parentheses
Arrow functions with one parameter can omit the parentheses around that parameter. However, if the parameter has a type annotation, it is a syntax error to omit the parentheses:
let friendNames =
friends.map(f: Friend => f.name);
const toString = thing: string => {
if (thing === true) return 'TRUE';
if (thing === false) return 'FALSE';
return thing.toString();
};
To fix this error, put a pair of parentheses around the parameter name and its type:
let friendNames =
friends.map((f: Friend) => f.name);
Alternatively, put a pair of parentheses around the parameter name, and leave
the :
and the return type outside:
const toString = (thing): string => {
if (thing === true) return 'TRUE';
if (thing === false) return 'FALSE';
return thing.toString();
};
Introduced in quick-lint-js version 2.7.0.