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Using fp-ts for Functional Programming in TypeScript

Creating Functions in JavaScript

Learn how to declare a function in JavaScript.

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There are many ways to create functions in JavaScript. Let’s see what they are.

The function keyword

The whole function consists of the following parts.

The basic syntax to create a function in JavaScript is using the function keyword. Let’s look at an example below.

C++
function example() {
    console.log('Print a message');
}
example();

We’ve created a simple function using the function keyword in the code snippet above. It logs Print a message to the console.

Creating function within a function

Since functions are first-class citizens in JavaScript, we can also do things like creating a function that itself creates functions. Let’s look at an example below.

C++
function withInnerFunction(outer) {
    return function ourInnerFunction(inner) {
        console.log(`Outer function received ${outer}, inner got ${inner}`);
    };
}
const returnedFunction = withInnerFunction('a');
// some time later in our program, we actually need to call returnedFunction 
returnedFunction('b');

In the code ...