Carmen  Grimes

Carmen Grimes

1610960765

Use Function Expressions Instead of Function Declarations in JavaScript

This articles aims to share why using function expressions is generally preferred over using function declarations. At work, I have observed different ways of creating functions in the codebase — and that lead me to search for answers on when to use which (declaration versus expression).

JavaScript has two different ways of creating functions. Function declarations have been used for a long time, but the usage of function expressions have been gradually taking over.

#programming #javascript #web-development #developer

What is GEEK

Buddha Community

Use Function Expressions Instead of Function Declarations in JavaScript
Madyson  Reilly

Madyson Reilly

1601069940

Function Expression vs Function Declaration in JavaScript

Function Expression vs Function Declaration in JavaScript.

It was until during one of the JavaScript mock interviews did I came across the term function expression.

The question was: What is the difference between these two syntax?

function x(){

}

let x = function(){

}

I was clueless for a moment. After thinking a little, I could only come up with: the second syntax invokes an _anonymous _function and is assigned to a variable.

I was alien to the term hoisting.

In this article, we will acquaint ourselves with three simple terms: function declaration,_ function expression, _and hoisting.

What is function declaration?

Function declaration is also known as _function statement. _It contains the name of the function, parameters, and a return statement. **Naming the function **is what sets function declaration apart. Parameters and return statement is optional.

Image for post

Function Declaration

What is function expression?

Function expression also has a name, parameters, and return statement. All of which are optional. The important thing to bear in mind is: the function here is _assigned _to a JavaScript variable.

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Function Expression

#function-expression #function-declaration #functions-in-javascript #coding #javascript #express

Vincent Lab

Vincent Lab

1605017502

The Difference Between Regular Functions and Arrow Functions in JavaScript

Other then the syntactical differences. The main difference is the way the this keyword behaves? In an arrow function, the this keyword remains the same throughout the life-cycle of the function and is always bound to the value of this in the closest non-arrow parent function. Arrow functions can never be constructor functions so they can never be invoked with the new keyword. And they can never have duplicate named parameters like a regular function not using strict mode.

Here are a few code examples to show you some of the differences
this.name = "Bob";

const person = {
name: “Jon”,

<span style="color: #008000">// Regular function</span>
func1: <span style="color: #0000ff">function</span> () {
    console.log(<span style="color: #0000ff">this</span>);
},

<span style="color: #008000">// Arrow function</span>
func2: () =&gt; {
    console.log(<span style="color: #0000ff">this</span>);
}

}

person.func1(); // Call the Regular function
// Output: {name:“Jon”, func1:[Function: func1], func2:[Function: func2]}

person.func2(); // Call the Arrow function
// Output: {name:“Bob”}

The new keyword with an arrow function
const person = (name) => console.log("Your name is " + name);
const bob = new person("Bob");
// Uncaught TypeError: person is not a constructor

If you want to see a visual presentation on the differences, then you can see the video below:

#arrow functions #javascript #regular functions #arrow functions vs normal functions #difference between functions and arrow functions

Nat  Kutch

Nat Kutch

1596848280

From imperative to declarative JavaScript

Introduction

In this post, I will explain why declarative code is better than imperative code.

Then I will list some techniques to convert imperative JavaScript to a declarative one in common situations, defining key terms along the way.

Why declarative ?

First, let’s define what declarative and imperative mean.

Declarative code is one that highlights the intent of what it’s doing.

It favors the “what” over the “how”.

In other words, the exact implementations actually doing the work (aka the “how”) are hidden in order to convey what that work actually is (aka the “what”).

At the opposite, imperative code is one that favors the “how” over the “what”.

Let’s see an example:

The snippet below perform two things: it computes the square of x, then check if the result is even or not.

// imperative way

	const x = 5;

	const xSquared = x * x;

	let isEven;

	if (xSquared % 2 === 0) {
	  isEven = true;
	} else {
	  isEven = false;
	}
view raw
block1.js hosted with ❤ by GitHub

Here, we can see that we finally get isEven after several steps that we must follow in order.

These steps describe “how” we arrive to know if the square of x is even, but that’s not obvious.

If you take a non-programmer and show him this, he might have a hard time deciphering it.

Now let’s see another snippet where I introduce a magic isSquareEven function that performs the two same things than the previous one.

#functional-programming #javascript #javascript-tips #programming #declarative-programming #function

Kieran  Stroman

Kieran Stroman

1591892460

JavaScript course : Function Declaration Vs Function expression (Difference)

Hi there everyone, in this video we’ll be learning about difference between function declaration and function expression in JavaScript. Syntax difference and hoisting difference explained.

#javascript #declaration #expression

CSS Boss

CSS Boss

1606912089

How to create a calculator using javascript - Pure JS tutorials |Web Tutorials

In this video I will tell you How to create a calculator using javascript very easily.

#how to build a simple calculator in javascript #how to create simple calculator using javascript #javascript calculator tutorial #javascript birthday calculator #calculator using javascript and html