Javascript – using default values for function parameters and when destructuring

DanielOctober 22, 2021October 26, 2021

I still find myself writing code like the one below:

function myFunction(name) {
    if (typeof name !== 'undefined') {
            name = "unknown person";
    }
}

Even if with the ES6 default values for paramters the code can be made just into this:

function myFunction(name = "unknown person") {
    // code here
}

And we can have the default values even when using the destructuring statements.

Let's say that we have:

const myName = {
    first: "Js",
    last: "Craft",
};
const { prefix, first, last } = myName; 
console.log(prefix + " " + first + " " + last);
// will output: undefined Js Craft
// because prefix is not set in the myName obj

But, if we define default values for the destructed properties:

const myName = {
    first: "Js",
    last: "Craft",
};
const { prefix = "Mr", first, last } = myName; 
console.log(prefix + " " + first + " " + last);
// it will output: Mr Js Craft

So, keep calm and use default values!