Named

--- Named function expressions --- A function expression may carry a name. Unlike a function *declaration*, that name is visible only inside the expression's own body — for self-reference/recursion — and never leaks to the enclosing scope.

// Recursion via the expression's own name.
const factorial = function fact(n: number): number {
    if (n <= 1) {
        return 1;
    }
    return n * fact(n - 1);
};
console.log(factorial(5));  // 120

// The name coexists with variables captured from the enclosing scope.
const offset = 100;
const sumTo = function rec(n: number): number {
    if (n === 0) {
        return offset;
    }
    return n + rec(n - 1);
};
console.log(sumTo(4));  // 100 + 4 + 3 + 2 + 1 = 110

// The name is private to the body: outside, only `factorial`/`sumTo` exist,
// not `fact`/`rec`. (Referencing `fact` here would be a compile error.)

// A decorative name (not used for recursion) is fine too.
const greet = function greeter(): string {
    return "hello";
};
console.log(greet());  // hello

View source on GitHubexamples/function_expressions/named.ts

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