Roadmap

    1 - Primitive Types

    Primitive Types

    Before we dig into Typescript specific types let's look at some of the primitive types that we already know from JavaScript and can also use in Typescript.

    string, number, and boolean

    JavaScript has three very commonly used primitives: string, number, and boolean. Each has a corresponding type in TypeScript.

    As you might expect, these are the same names you’d see if you used the JavaScript typeof operator on a value of those types:

    • string represents string values like "Hello, world"
    • number is for numbers like 42. JavaScript does not have a special runtime value for integers, so there’s no equivalent to int or float - everything is simply number
    • boolean is for the two values true and false

    To declare the type for a variable or function we append it to the name when initializing by using a semi-colon : followed by the type.

    ts
    // Examples
     
    let fullName: string = "John Doe";
    let age: number = 43;
    let isAdult: boolean = true;
     
    console.log(typeof fullName); // string
    console.log(typeof age); // number
    console.log(typeof isAdult); // boolean

    Next, Let look at some more primitive types that we already know from JasvaScript