Hoisting
A lot of developers get unexpected results when they are not clear about the concept of hoisting in JavaScript. In Javascript, you can call a function before it is defined and you won’t get an error ‘Uncaught ReferenceError’. The reason behind this is hoisting where the Javascript interpreter always moves the variables and function declaration to the top of the current scope (function scope or global scope) before the code execution. Let’s understand this with an example.
Example: Take a look at the code given below.
function cowSays(sound) {
console.log(sound);
}
cowSays('moo');
Output:
moo
Example: here, we invoke our function before we declare it (with hoisting)
cowSays('moo');
function cowSays(sound) {
console.log(sound);
}
Output:
moo
7 JavaScript Concepts That Every Web Developer Should Know
JavaScript is Everywhere. Millions of web pages are built on JavaScript and it’s not going anywhere at least for now. On one side HTML and CSS give styling to the web pages but on the other side, it’s the magic of JavaScript that makes your web page alive. Today this language is not just limited to your web browser. You can also use it for server-side applications. Isn’t it cool to use a single language for both client-side and server-side applications? A single language fulfills both of the purposes and this is the main reason TONs of job postings are there for JavaScript developers in the tech industry.
According to the Stack Overflow Developer Survey 2019, JavaScript is the #1 programming language. The language is widely used by 95% of all websites Whether it’s a small startup or a big company, most of them are working on some kind of website or an app that requires a good knowledge of this language. A lot of frameworks and libraries are there for JavaScript. These frameworks and libraries can be easily learned if your JavaScript fundamentals are clear. A lot of concepts are confusing and overwhelming for developers but a good knowledge of these concepts will help you in the long run. Frameworks and libraries come and go but the fundamentals always remain the same. It’s easy to build any kind of application and learn any framework and libraries if the fundamentals are clear. Also, it will help you in interviews as well. Let’s discuss some of the basic concepts of JavaScript which are important to learn for any JavaScript developer. Become a good front-end developer with w3wiki JavaScript Foundation – Self-Paced and learn all the aspects of web development with ease.
These are the 7 concepts:
Table of Content
- Scope
- IIFE (Immediately Invoked Function Expression)
- Hoisting
- Closures
- Callbacks
- Promises
- Async & Await
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