Top 10 JavaScript Concepts Programmers You Should Know In 2024

Want to create scalable Node.js apps? Discover how to have JavaScript work for you, not against you.

JavaScript Concepts

From an out-of the-ordinary concept, Node.js became a mainstay in record time. These days, building web apps, systems software, and more is essentially expected of web developers. Express, build-chain tools like Webpack, and a number of utilities for every need make Node a highly popular method to use the power and expressiveness of JavaScript on the back end. Server-side Node frameworks like Express and build-chain tools like Webpack.

Node is still the flagship JavaScript platform on the server even if Deno and Bun now provide competition.

Node owes much for its great popularity to JavaScript Concepts. JavaScript is a multipuradigm language supporting object-oriented programming, reactive programming, and functional programming among other many programming approaches. It lets the developer take use of the several programming approaches and be adaptable.

JavaScript may be a two-edged blade, too. JavaScript’s multipuradigm character implies almost everything is changeable. Consequently, while developing Node.js code, you cannot ignore the possibility of object and scope modification. Using recursion for significant iterations is risky as JavaScript lacks tail-call optimization — that is, the ability of recursive functions to reuse stack frames for recursive calls. Apart from such dangers, Node is single-threaded, hence developers must design asynchronous code. Node also struggles from swallowing mistakes and facepalms typical of all languages.

If utilized sensibly, JavaScript may be a blessing; if used carelessly, it can be a curse. Following organized guidelines, design patterns, important ideas, and basic rules of thumb will help you decide the best way to handle an issue. Which fundamental ideas should developers of Node.js grasp? I think these ten JavaScript ideas are most important for creating scalable and effective Node.js programs.

JavaScript closure

JavaScript closures are inner functions with access to the scope of their outer function even following the return of control. Closing the inner function renders the variables in it private. Functional programming has become somewhat popular, hence Node developers now always carry closures in their toolkit. JavaScript has a basic closure like this:

let count = (function () {
     var _counter = 0;
     return function () {return _counter += 1;}
})();

count();
count();
count();

>// the counter is now 3

The variable count serves an outside purpose. Running just once, the outer function sets the counter to zero and generates an inside function. The inner function alone may access the counter variable, so it functions as a private variable.

Here the example is a higher-order function — that is, a metafunction, a function that either accepts or returns another function. Many additional uses call for closures. Closing occurs anytime one defines a function inside another function and the inner function gains both its own scope and access to the parent scope — that is, the inner function may “see” the outer variables, but not vice versa.

This is especially useful with functional approaches such as map(innerFunction), because innerFunction may leverage variables specified in the outer scope.

JavaScript prototype tools

Every JavaScript function has a prototype property designed for attachment of properties and methods. This attribute is not countable. It lets the developer mark objects with member functions or attachments. JavaScript allows inheritance just through the prototype property. Regarding an inherited object, the prototype property links to its parent. One often used technique to link ideas to a function is to apply prototypes as seen here:

function Rectangle(x, y) {
     this.length = x;
     this.breadth = y;
}

Rectangle.prototype.getDimensions = function () {
     return { length : this._length, breadth : this._breadth };
};

Rectangle.prototype.setDimensions = function (len, bred) {
     this.length = len;
     this.breadth = bred;
};

Modern JavaScript still runs on the prototype system beneath the hood even if it has somewhat advanced class support. Much of the flexibility of language comes from this.

Creating private properties with hash names

In the past, a variable was meant to be private by convention of prefixing it with an underscore. Still, this was only a recommendation — not a platform-enforced ban. Modern JavaScript provides classes and hashtag private members:

class ClassWithPrivate {
  #privateField;
  #privateMethod() { }
}

A more recent and extremely welcome tool in JavaScript are private hash names! Recent Node versions and browsers allow it; Chrome devtools enables you conveniently directly access private variables.

Clearly defining private properties with closures

Another method occasionally seen for overcoming JavaScript’s prototype system’s absence of private attributes is employing a closure. As the preceding example shows, modern JavaScript enables you specify private properties by using the hashtag prefix. That does not apply, though, for the JavaScript prototype system. Also, this is a tactic you will often discover in code and it’s crucial to grasp what it is doing.

Closure-based definition of private properties allows one to replicate a private variable. The object itself should clearly specify the member functions requiring access to secret attributes. Making private properties with closures follows this syntax:

function Rectangle(_length, _breadth) {
     this.getDimensions = function () {
     return { length : _length, breadth : _breadth };
     };

     this.setDimension = function (len,bred) {
     _length = len;
     _breadth = bred
     };
}

JavaScript components

JavaScript used to have no module system once upon a time, hence developers used a cunning approach known as the module pattern to construct something that would function. Two module systems emerged as JavaScript developed: the CommonJS include syntax and the ES6 depend on syntax.

CommonJS has been used historically by Node; browsers use ES6. Recent Node iterations, in the last few years, have also supported ES6, however. ES6 modules are now the trend; eventually, JavaScript will have just one module syntax to apply. ES6 looks like this (where we import a default module following export of a default module):

// Module exported in file1.js…
export default function main() { }
// …module imported in file2.js
import main from "./file1";

CommonJS will still be visible to you, and occasionally you will need to import a module using it. Export and subsequently import a default module using CommonJS looks like follows:

Useful elements for arguments

JavaScript has some strong tools for handling arguments even if it cannot enable method overloading (because it can manage arbitrary parameter counts on methods). One can define a function or method with default values by first:

function greet(name = 'Guest')
 { 
   console.log(`Hello, ${name}!`); 
 } 
  greet(); // Outputs: Hello, Guest! 
  greet('Alice'); // Outputs: Hello, Alice!

You may also welcome and manage all the arguments at once to manage any quantity of passed ones. This gathers all the parameters into an array via the rest operator:

function sum(...numbers) { 
  return numbers.reduce((total, num) => total + num, 0); 
} 

console.log(sum(1, 2, 3)); // Outputs: 6 
console.log(sum(4, 5)); // Outputs: 9

You may always verify them if you truly have to handle different argument setups:

function findStudent(firstName, lastName) {
    if (typeof firstName === 'string' && typeof lastName === 'string') {
        // Find by first and last name
    } else if (typeof firstName === 'string') {
        // Find by first name
    } else {
        // Find all students
    }
}

findStudent('Alice', 'Johnson');  // Find by first and last name
findStudent('Bob');               // Find by first name
findStudent(); // Find all

Keep in mind too that JavaScript features a built-in arguments array. Every function or method automatically generates the arguments varied, storing all the supplied values to the call.

EndNote

As you get acquainted with Node, you will see there are several approaches to practically tackle virtually any problem. The correct course is not always clear-cut. A given problem might have numerous reasonable solutions at times. Knowing the several choices at hand helps.

Basic knowledge of the ten JavaScript ideas covered here will help every Node developer. Still, they represent the tip of the iceberg. JavaScript is a sophisticated and quite difficult language. Using it more will help you to realize how big JavaScript actually is and how much you can achieve with it.