7 JavaScript Concepts That Every Web Developer Should Know
1. Scopes 🤗
The understanding scope will make your code stand out, reduce errors and help you make powerful design patterns with it
Local and Global
There are two kinds of scope — global scope and local scope
Variables defined inside a function are in local scope while variables defined outside of a function are in the global scope. Each function when invoked creates a new scope.
JavaScript has function scope: Each function creates a new scope.
// Global Scope
function someFunction() {
// Local Scope #1
function someOtherFunction() {
// Local Scope #2
}
}// Global Scope
function anotherFunction() {
// Local Scope #3
}
// Global Scope
2. IIFE 😎
Immediately Invoked Function Expression
IIFE is a function expression that automatically invokes after completion of the definition. The parenthesis () plays important role in IIFE pattern. In JavaScript, parenthesis cannot contain statements; it can only contain an expression.
(function () {
//write your js code here
})();3. Hoisting 😉
Hoisting is JavaScript’s default behavior of moving all declarations to the top of the current scope (to the top of the current script or the current function).
4. Closures 🙄
A closure is a combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In JavaScript, closures are created every time a function is created, at function creation time. To use a closure, define a function inside another function and expose it.
One powerful use of closures is to use the outer function as a factory for creating functions that are somehow related. Using closures as function factories is a great way to keep your JavaScript DRY. Five powerful lines of code allow us to create any number of functions with similar, yet unique purposes
5. Callbacks 📞
A callback is a function passed into another function as an argument to be executed later
I will call back later!
A callback is a function passed as an argument to another function
This technique allows a function to call another function
A callback function can run after another function has finished
6. Promises 🤝
The Promise object represents the eventual completion (or failure) of an asynchronous operation and its resulting value.
7. Async & Await 😮
The word “async” before a function means one simple thing: a function always returns a promise.
The keyword “await” makes JavaScript wait until that promise settles and returns its result.
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Thank you :)
Happy.Coding()
