Module_2_B.md

Functions

JS functions are values in themselves, and can be used accordingly.

Different ways to declare functions

Standard

function inchToCm(inches) {
    const cm = inches * 2.54;
    return cm;
};

Function Expression

Storing an anonymous function as value in a variable.

const inchtoCm = function(inches) {
    return inches * 2.54;
};

Arrow Function

const inchtoCm = (inches) => {
    return inches * 2.54;
};

Implicit Return

const inchtoCm = (inches) => inches * 2.54;

If you have only a single parameter, you can remove the parenthesis.

const inchtoCm = inches => inches * 2.54;

IIFE: Immediatelly Invoked Functional Expression

A way to run an anonymous function immediatelly when it is created.

(function(){
    console.log('Running this Function');
}) ();

Returning Objects

function makeABaby(first, last){
    const baby = {
        name: `${first} ${last}`,
        age: 0
    }

    return baby;
}

const makeABaby = (first, last) => {
    return {
        name: `${first} ${last}`,
        age: 0
    }
}

const makeABaby = (first, last) => ({ name: `${first} ${last}`, age: 0 });

Methods

A method is simply a function that lives insite of an object. console.log(): log is a function that li

Callback Functions

Something that will happen when something is done, such as clicking a button.

function handleclick(){
    console.log('Message');
}

button.addEventListener('click', handleClick)

button.addEventListener('click', function(){
        console.log('Message');
})

or after a timeout: the below will run functionName after 1000 miliseconds (one second). You can do it as above by either calling a function you declared beforehand

setTimeOut(functionName, 1000);

Or declaring it directly within setTimeOut as an anonymous function

setTimeOut(function(){
    console.log('Message');
}, 1000);

Or an arrow function

setTimeOut(()=> { console.log('Message') }, 100));

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Hoisting - A fuction declared with the function keyword, is hoisted by JS to the top of the file, so it doesn't care about the order of the document. You can call it even before it's declaration.

Curly Brackets {} mean either a block of code or the creation of an object

Parenthesis () always run first in JS.

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