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Learn TypeScript: The Complete Course for Beginners

Returning nothing with Void

Explore the void keyword in TypeScript to understand how it marks functions that return no value. Learn why explicitly setting a function's return type to void helps avoid errors by preventing unintended return values across multiple return statements.

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Void means nothing. However, undefined can be assigned to void. The operation of setting undefined to void is not useful per se. However, a function that returns nothing should be marked with the reserved void keyword.

TypeScript 3.3.4
function executeFunctionWithoutReturnType(): void {
    return undefined;
}
let returnType = executeFunctionWithoutReturnType(); // Hover the variable to see "void"
console.log(returnType);

If a function is not explicitly marked with void as the return value, then by default, TypeScript will mark the return value as void. This may be problematic, because a programmer may return anything within the function. If it is explicitly set to void, ...