Overview of React Hooks

Overview of React Hooks

In this article, we are going to go over React Hooks. This new feature is currently in the alpha stage. With React Hooks, we will be able to write functional components that have a state; no need to use a class component for state anymore!

In this article, we are going to go over React Hooks. This new feature is currently in the alpha stage. With React Hooks, we will be able to write functional components that have a state; no need to use a class component for state anymore!

Learn what's new with React Hooks. For example, use state in a functional component.

Table of Contents

  1. React Hooks
  2. What Is a "Hook"?
  3. Using React Hooks in Projects
  4. What State Looks Like Currently
  5. What State Can Look Like With React Hooks
  6. Why the Square Brackets
  7. Multiple State Hooks
  8. The Effect Hook
  9. Conclusion
React Hooks

React is constantly giving us cool new updates. Currently, in React v16.8.0-alpha.1, we have React Hooks! What if I told you Hooks got rid of the major need for class components? This new feature may make your code more concise. Don’t we all want that?

But what is all the fuss with React Hooks? Why should I stop using class components? By all means, no need to stop using them. There is no plan to get rid of class components and if the developer wants to, the transition to switch to React Hooks is going to be seamless.

What Is a "Hook"?

React Hooks are a way to "hook" into a functional component. Functional components have never been able to hold a state, but with Hooks, it gives them the power to do so now.

If we were to head over to React docs on Hooks, they said it best with:

Hooks are an upcoming feature that lets you use state and other React features without writing a class. Source

State is written in a much cleaner way and setting or updating that state can be declared in as little as one line.

Then you have lifecycle methods like componentDidMount or componentDidUpdate that will be taken care of by useEffect. Hooks are powerful, and it allows for functional components to harness that power.

Using React Hooks in Projects

Now that we have a basic understanding of what React Hooks are, are we ready to use it in our projects? To get the current version of React into your project and start using React Hooks, simply run this command in your IDE:

npm install -S [email protected] [email protected] 

What State Looks Like Currently

In a class component, we are able to declare state and set that state with setState We are familiar with it looking something like this:

// 24 lines of code 

import React from "react"; 
import ReactDOM from "react-dom"; 

class ClassExample extends React.Component { 
  constructor(props) { 
    super(props); 
    this.state = { 
      phrase: "My Favorite Color Is " 
    }; 
  } 

render() { 
  return ( 
  <div> 
    <p>{this.state.phrase}</p> 
    <button onClick={() => this.setState({ phrase: this.state.phrase + "Blue" })}> Reveal the Color! 
    </button> 
  </div> 
  ); 
} 
} 

ReactDOM.render(<ClassExample />, document.getElementById("root")); 

The CodeSandbox for the above code can be found here.

In this example, we are declaring our state to be the phrase, "My Favorite Color Is ". We then create a button that when clicked, activates the setState and adds on the string, "Blue" to the phrase.

The output of this component would look like this:

And once the button is clicked, we should see this:

What State Can Look Like With React Hooks

If we took that same logic from the class component, put it into a functional component, and used React Hooks instead, we could cut out a lot of lines of code. Let’s see how that would look like.

// 17 lines of code 
import React, { useState } from "react"; 
import ReactDOM from "react-dom"; 

function HooksExample() { 
  const [phrase, setPhrase] = useState("My Favorite Color Is "); 

  return ( 
    <div> 
      <p>{phrase}</p> 
      <button onClick={() => setPhrase(phrase + "Blue")}> Reveal the Color! 
      </button> 
    </div> 
  ); 
} 
ReactDOM.render(<HooksExample />, document.getElementById("root"));

The CodeSandbox for the above code can be found here.

Hooks are an upcoming feature that lets you use state and other React features without writing a class. Source

We see here that state looks different, much different. Besides the keyword useState, we don’t even see state being used at all.

In this line:

const [phrase, setPhrase] = useState("My Favorite Color Is ");&nbsp;

This is where our state is being set. The two values, phrase and setPhrase are placeholders. We also see a new feature, useState.

  1. React Hooks
  2. What Is a "Hook"?
  3. Using React Hooks in Projects
  4. What State Looks Like Currently
  5. What State Can Look Like With React Hooks
  6. Why the Square Brackets
  7. Multiple State Hooks
  8. The Effect Hook
  9. About Auth0
  10. Conclusion

By using setPhrase within the React element being rendered, we are able to set a new state value and reveal the favorite color after the button is clicked.

The difference in the number of lines between these two examples is seven lines, but that can grow so much depending on your component. But the big difference is that we now can declare our state in a single line! We are able to replace our class constructor for a single function call.

By looking at useState a little more, this is the Hook that allows for the us to add in state to our functional component. You can read more about that in the React docs here!

Also, notice that in the Hooks example, it was a functional component. Using state in a functional component, who would have thought!

Why the Square Brackets?

This is using the JavaScript syntax, ["array destructuring"](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment ""array destructuring""). Array destructing is when we are able to "unpack" values from an array and assign them to variables.

We are able to give the variables our own names, like phrase and setPhrase and then the useState knows that those two values are what it's going to be using. Once setting those two variables, the useState will be able to map over the values and know that the first value has the name of phrase and the second value has a name of setPhrase.

const [firstvalue, secondvalue] = useState(0);&nbsp;

Multiple State Hooks

Want to use more than just one state hook in a component? React allows for multiple state hooks in one component:

function LotsOfStates() { 
  const [name, setName] = useState("Sarah"); 
  const [color, setColor] = useState("Blue"); 
  const [shopping, setList] = useState([{ item: "Almond Milk" }]);&nbsp;

We are able to give different names to particular states, that way things are kept organized. Rather than using the word, state, we give it a name like, color or shopping so we know exactly which one we are working with.

The Effect Hook

Another neat feature of React Hooks is the use of useEffect. This will handle the lifecycle methods that we would want to use in our React code. The following code is based on an example presented in the React docs:

import { useState, useEffect } from 'react'; 

function Example() { 
  const [count, setCount] = useState(0); 

// Similar to componentDidMount and componentDidUpdate: 
useEffect(() => { 
  // Update the document title using the browser API 
  document.title = `You clicked ${count} times`; 
}); 

return ( 
  <div> 
    <p>You clicked {count} times</p> 
    <button onClick={() => setCount(count + 1)}> 
      Click me 
    </button> 
  </div> 
  ); 
}

Source

The useEffect hook replaces the following lifecycle methods:

  1. React Hooks
  2. What Is a "Hook"?
  3. Using React Hooks in Projects
  4. What State Looks Like Currently
  5. What State Can Look Like With React Hooks
  6. Why the Square Brackets
  7. Multiple State Hooks
  8. The Effect Hook
  9. About Auth0
  10. Conclusion

In a sense, it combines the power of these three, and makes one mega lifecycle method!

The Effect Hook tells the component what we would like it to do at a certain time. After render, it will take care of any logic within the useEffect function. It could be something like the React docs example above or even to fetch data from an API.

What is JavaScript – All You Need To Know About JavaScript

What is JavaScript – All You Need To Know About JavaScript

In this article on what is JavaScript, we will learn the basic concepts of JavaScript.

After decades of improvement, JavaScript has become one of the most popular programming languages of all time. It all started in the year 1995 when Brendan Eich created JavaScript in a span of 10 days. Since then, it has seen multiple versions, updates and has grown to the next level.

Here’s a list of topics that I’ll be covering in this blog:

  1. What is JavaScript
  2. What can JavaScript do?
  3. JavaScript Frameworks
  4. The Big Picture: HTML, CSS & JavaScript
  5. Benefits of JavaScript
  6. Fundamentals of JavaScript
    VariablesConstantsData TypesObjectsArraysFunctionsConditional statementsLoopsSwitch case
What is JavaScript?

JavaScript is a high level, interpreted, programming language used to make web pages more interactive.

Have you ever thought that your website is missing something? Maybe it’s not engaging enough or it’s not as creative as you want it to be. JavaScript is that missing piece which can be used to enhance web pages, applications, etc to provide a more user-friendly experience.

What is JavaScript?

JavaScript is the language of the web, it is used to make the web look alive by adding motion to it. To be more precise, it’s a programming language that let’s you implement complex and beautiful things/design on web pages. When you notice a web page doing more than just sit there and gawk at you, you can bet that the web page is using JavaScript.

Feature of JavaScript

Scripting language and not Java: In fact, JavaScript has nothing to do with Java. Then why is it called “Java” Script? When JavaScript was first released it was called Mocha, it was later renamed to LiveScript and then to JavaScript when Netscape (founded JavaScript) and Sun did a license agreement. Object-based scripting language which supports polymorphism, encapsulation and to some extent inheritance as well.**Interpreted language: **It doesn’t have to be compiled like Java and C which require a compiler.JavaScript runs in a browser: You can run it on Google Chrome, Internet Explorer, Safari, etc. JavaScript can execute not only in the browser but also on the server and any device which has a JavaScript Engine.

What is JavaScript – Stackoverflow stats

Currently, we have 100s of programming languages and every day new languages are being created. Among these are few powerful languages that bring about big changes in the market and JavaScript is one of them.

JavaScript has always been on the list of popular programming languages. According to StackOverflow, for the 6th year in a row, JavaScript has remained the most popular and commonly used programming language.

What can JavaScript do?

JavaScript is mainly known for creating beautiful web pages & applications. An example of this is Google Maps. If you want to explore a specific map, all you have to do is click and drag with the mouse. And what sort of language could do that? You guessed it! It’s JavaScript.JavaScript can also be used in smart watches. An example of this is the popular smartwatch maker called Pebble. Pebble has created Pebble.js which is a small JavaScript Framework that allows a developer to create an application for the Pebble line of watches in JavaScript.

What is JavaScript – Applications of JavaScript
Most popular websites like Google, Facebook, Netflix, Amazon, etc make use of JavaScript to build their websites.Among things like mobile applications, digital art, web servers and server applications, JavaScript is also used to make Games. A lot of developers are building small-scale games and apps using JavaScript.## JavaScript Frameworks

One major reason for the popularity of JavaScript is the JavaScript Frameworks. Here’s a brief introduction of the most trending JavaScript frameworks :

  1. AngularJS is Google’s web development framework which provides a set of modern development and design features for rapid application development.

  2. ReactJS is another top JavaScript framework mainly maintained by Facebook and it’s behind the User Interface of Facebook and Instagram, showing off its efficiency in maintaining such high traffic applications.

What is JavaScript – JavaScript Frameworks

  1. MeteorJS is mainly used for providing back-end development. Using JavaScript on the back-end to save time and build expertise is one of the major ideas behind Meteor.

  2. jQuery can be used when you want to extend your website and make it more interactive. Companies like Google, WordPress and IBM rely on jQuery.

The Big Picture: HTML, CSS & JavaScript

Anyone familiar with JavaScript knows that it has something to do with HTML and CSS. But what is the relationship between these three? Let me explain this with an analogy.

What is JavaScript – HTML, CSS and JavaScript

Think of HTML (HyperText Markup Language) as the skeleton of the web. It is used for displaying the web.

On the other hand, CSS is like our clothes. We put on fashionable clothes to look better. Similarly, the web is quite stylish as well. It uses CSS which stands for Cascading Style Sheets for styling purpose.

Then there is JavaScript which puts life into a web page. Just like how kids move around using the skateboard, the web also motions with the help of JavaScript.

Benefits of JavaScript

There has to be a reason why so many developers love working on JavaScript. Well, there are several benefits of using JavaScript for developing web applications, here’s a few benefits:

It’s easy to learn and simple to implement. It is a weak-type programming language unlike the strong-type programming languages like Java and C++, which have strict rules for coding.

It’s all about being fast in today’s world and since JavaScript is mainly a client-side programming language, it is very fast because any code can run immediately instead of having to contact the server and wait for an answer.

Rich set of frameworks like AngularJS, ReactJS are used to build web applications and perform different tasks.

**Builds interactive websites: **We all get attracted to beautifully designed websites and JavaScript is the reason behind such attractive websites and applications.

JavaScript is an interpreted language that does not require a compiler because the web interprets JavaScript. All you need is a browser like Google Chrome or Internet Explorer and you can do all sorts of stuff in the browser.

JavaScript is platform independent and it is supported by all major browsers like Internet Explorer, Google Chrome, Mozilla Firefox, Safari, etc.

JavaScript Fundamentals

In this What is JavaScript blog, we’ll cover the following basic fundamentals of JavaScript
VariablesConstantsData TypesObjectsArraysFunctionsConditional statementsLoopsSwitch case## Variables

Variable is a name given to a memory location which acts as a container for storing data temporarily. They are nothing but reserved memory locations to store values.

What is JavaScript – Variables

To declare a variable in JavaScript use the ‘let’ keyword. For example:

let age;
age=22;

In the above example, I’ve declared a variable ‘age’ by using the ‘let’ keyword and then I’ve stored a value (22) in it. So here a memory location is assigned to the ‘age’ variable and it contains a value i.e. ’22’.

Constants

Constants are fixed values that don’t change during execution time.

To declare a constant in JavaScript use the ‘const’ keyword. For example:

const mybirthday;
mybirthday='3rd August'; 

Data types

You can assign different types of values to a variable such as a number or a string. In JavaScript, there are two categories of data types :

What is JavaScript – Data Types

Objects

An object is a standalone entity with properties and types and it is a lot like an object in real life. For example, consider a girl, whose name is Emily, age is 22 and eye-color is brown. In this example the object is the girl and her name, age and eye-color are her properties.

What is JavaScript – Objects example

Objects are variables too, but they contain many values, so instead of declaring different variables for each property, you can declare an object which stores all these properties.

To declare an object in JavaScript use the ‘let’ keyword and make sure to use curly brackets in such a way that all property-value pairs are defined within the curly brackets. For example:

let girl= {
name: 'Emily',
age: 22,
eyeColour: 'Brown'
};

In the above example, I’ve declared an object called ‘girl’ and it has 3 properties (name, age, eye colour) with values (Emily, 22, Brown).

Arrays

An array is a data structure that contains a list of elements which store multiple values in a single variable.

For example, let’s consider a scenario where you went shopping to buy art supplies. The list of items you bought can be put into an array.

What is JavaScript – Arrays example

To declare an array in JavaScript use the ‘let’ keyword with square brackets and all the array elements must be enclosed within them. For example:

let shopping=[];
shopping=['paintBrush','sprayPaint','waterColours','canvas'];

In the above example I’ve declared an array called ‘shopping’ and I’ve added four elements in it.

Also, array elements are numbered from zero. For example this is how you access the first array element:

shopping[0];		

Functions

A function is a block of organised, reusable code that is used to perform single, related action.

Let’s create a function that calculates the product of two numbers.

To declare a function in JavaScript use the ‘function’ keyword. For example:

function product(a, b) {
return a*b;
}

In the above example, I’ve declared a function called ‘product’ and I’ve passed 2 parameters to this function, ‘a’ and ‘b’ which are variables whose product is returned by this function. Now, in order to call a function and pass a value to these parameters you’ll have to follow the below syntax:

product(8,2);

In the above code snippet I’m calling the product function with a set of values (8 & 2). These are values of the variables ‘a’ and ‘b’ and they’re called as arguments to the function.

Conditional statements – if

Conditional statement is a set of rules performed if a certain condition is met. The ‘if’ statement is used to execute a block of code, only if the condition specified holds true.

What is JavaScript – if flowchart

To declare an if statement in JavaScript use the ‘if’ keyword. The syntax is:

if(condition) {
statement;
}

Now let’s look at an example:

let numbers=[1,2,1,2,3,2,3,1];
if(numbers[0]==numbers[2]) {
console.log('Correct!');
}

In the above example I’ve defined an array of numbers and then I’ve defined an if block. Within this block is a condition and a statement. The condition is ‘(numbers[0]==numbers[2])’ and the statement is ‘console.log(‘Correct!’)’. If the condition is met, only then the statement will be executed.

Conditional statements- Else if

Else statement is used to execute a block of code if the same condition is false.

What is JavaScript – Else-if flowchart

The syntax is:

if(condition) {
statement a;
}
else (condition) {
statement b;
}

Now let’s look at an example:

let numbers=[1,2,1,2,3,2,3,1];
if(numbers[0]==numbers[4] {
console.log("Correct!");
}
else {
console.log("Wrong, please try again");
}

In the above example, I’ve defined an if block as well as an else block. So if the conditions within the if block holds false then the else block gets executed. Try this for yourself and see what you get!

**Loops **

Loops are used to repeat a specific block until some end condition is met. There are three categories of loops in JavaScript :

  1. while loop
  2. do while loop
  3. for loop
While loop

While the condition is true, the code within the loop is executed.

What is JavaScript – while loop flowchart

The syntax is:

while(condition) {
loop code;
}

Now let’s look at an example:

let i=0;
while(i < 5) {
console.log("The number is " +i);
i++;
}

In the above example, I’ve defined a while loop wherein I’ve set a condition. As long as the condition holds true, the while loop is executed. Try this for yourself and see what you get!

Do while loop

This loop will first execute the code, then check the condition and while the condition holds true, execute repeatedly.

What is JavaScript – Do while loop flowchart

Refer the syntax to better understand it:

do {
loop code;
} while(condition);

This loop executes the code block once before checking if the condition is true, then it will repeat the loop as long as the condition holds true.

Now let’s look at an example:

do {
console.log("The number is " +i);
i++;
}
while(i > 5);

The above code is similar to the while loop code except, the code block within the do loop is first executed and only then the condition within the while loop is checked. If the condition holds true then the do loop is executed again.

For loop

The for loop repeatedly executes the loop code while a given condition is TRUE. It tests the condition before executing the loop body.

What is JavaScript – for loop flowchart

The syntax is:

for(begin; condition; step) {
loop code;
}

In the above syntax:

  • begin statement is executed one time before the execution of the loop code
  • condition defines the condition for executing the loop code
  • step statement is executed every time after the code block has been executed

For example:

for (i=0;i<5;i++) {
console.log("The number is " +i);
}

In the above example, I’ve defined a for loop within which I’ve defined the begin, condition and step statements. The begin statement is that ‘i=0’. After executing the begin statement the code within the for loop is executed one time. Next, the condition is checked, if ‘i<5’ then, the code within the loop is executed. After this, the last step statement (i++) is executed. Try this and see what you get!

Switch Case

The switch statement is used to perform different actions based on different conditions.

What is JavaScript – Switch case flowchart

Let’s look at the syntax for switch case:

switch(expression) {
case 1:
code block 1
break;
case 2:
code block 2
break;
default:
code block 3
break;
}

How does it work?

  • Switch expression gets evaluated once
  • Value of the expression is compared with the values of each case
  • If there is a match, the associated block of code is executed

Let’s try this with an example:

let games='football';
switch(games) {
case "throwball":
console.log("I dislike throwball!");
break;
case "football":
console.log("I love football!");
break;
case "cricket":
console.log("I'm a huge cricket fan!");
break;
default:
console.log("I like other games");
break;
}

In the above example the switch expression is ‘games’ and the value of games is ‘football’. The value of ‘games’ is compared with the value of each case. In this example it is compared to ‘throwball’, ‘cricket’ and ‘football’. The value of ‘games’ matches with the case ‘football’, therefore the code within the ‘football’ case is executed. Try this for yourself and see what you get!

With this, we come to the end of this blog. I hope you found this blog informative and I hope you have a basic understanding of JavaScript. In my next blog on JavaScript I’ll be covering in-depth concepts, so stay tuned.

Also, check out our video on JavaScript Fundamentals if you want to get started as soon as possible and don’t forget to leave a comment if you have any doubt and also, let us know whether you’d want us to create more content on JavaScript. We are listening!

Why ReactJS is better for Web Application Development?

Why ReactJS is better for Web Application Development?

Web Application Development is the point of contact for a business in today's digital era. It is important to choose the right platform for Web Application Development to build a high end Web

Web Application Development is essential for a business in today’s digital era. Finding the right platform for Web Application Development is important for building an effective Web Application that can enhance the overall customer engagement. Here’s what makes ReactJS a better option for building your next Web Application.