open-ended function arguments with TypeScript

Question

IMO, one of the main concerns of the TypeScript language is to support the existing vanilla JavaScript code. This is the impression I had at first glance. Take a look at the

Answer 1

The TypeScript way of doing this is to place the ellipsis operator (...) before the name of the argument. The above would be written as,

function sum(...numbers: number[]) {
    var aggregateNumber = 0;
    for (var i = 0; i < numbers.length; i++)
        aggregateNumber += numbers[i];
    return aggregateNumber;
}

This will then type check correctly with

console.log(sum(1, 5, 10, 15, 20));