TIL Rest Parameters

POSTED ON: Jun 28, 2020

You don't know how many params the function may use.

function add(...theArgs) {

    // return param1 + param2;
    let total = 0;

    for (let arg of theArgs) {
        total = total + parseInt(arg);
    }
    //foreach version
    theArgs.forEach(argument => {
        total += argument;
    })

    return total;
}

I originally used a for..in instead of a for..of.

The difference:

for..in iterates over all enumerable property keys of an object
for..of iterates over the values of an iterable object.

Another way would be to use a foreach loop.

TEST SUITE (using Jasmine):

describe('add()', () => {
    it('adds two numbers', () => {
        // arrange
        const num1 = 1;
        const num2 = 2;

        // act
        const result = add(num1, num2);

        // log
        console.log("result: ", result);

        // assert
        expect(result).toBe(3);
    });

    //remove x to add it as the testing suite
    xit('adds any ammount of numbers', () => {
        // arrange
        const num1 = 1;
        const num2 = 2;
        const num3 = 3

        // act
        const result = add(num1, num2, num3);

        // log
        console.log("result: ", result);

        // assert
        expect(result).toBe(6);
    });
});

rest
MDN Web Docs

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