Javascript method with type and default value

Question

I have seen code of the form

functionName(isTrue: ?boolean = true) { //I came know that isTrue is parameter, of boolean type with true as default value
    if(isTrue) {
        //true Block
    }
    else {
       //false block
    }
}

I am new to Javascript, and using react-native from 3 months. So I know that this is a kind of declaration of functions.

I want to know:

where is the documentation for such types of declarations.
if this kind of declaration is known by any name?

Ramaraja · Accepted Answer · 2020-04-19 12:13:07Z

1

I think you are confusing TypeScript with JavaScript. The code snippet you have posted is in TypeScript. TypeScript is a superset of JavaScript developed by Microsoft.

To understand more about how functions work in TypeScript refer this, https://www.typescriptlang.org/docs/handbook/functions.html

To understand and learn TypeScript, in general, I would suggest you start with the docs, https://www.typescriptlang.org/docs/home

Once you are done with that take some course on some online platform like Udemy, Pluralsight etc...

answered Apr 19, 2020 at 12:13

Ramaraja

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