This article is based on one I originally wrote on .dev.to back in 2022. Now it's here on my website too. 🙂 Read the original article on .dev.to
1. Destructuring with Aliases
const person = { firstName: 'John', lastName: 'Doe' };
const { firstName: first, lastName: last } = person;
console.log(first); // Output: John
console.log(last); // Doe2. Converting Strings to Numbers
This concise trick converts a string to a number using the unary plus operator. It's a concise alternative to parseInt() or Number().
const num = +"42";
console.log(typeof(num)) // number
console.log(+"asdf") // NaN
3. Numeric Separators
You can now easily separate numbers with just an _ . This will make life of developers working with large numbers more easier.
//old syntax
let number = 1243134123
//new syntax
let number = 1_243_134_123
console.log(number) // 12431341234. Get unique values from an array
We can extract unique values from an array i.e removing duplicate values in an array by simply using the Set object and Spread operator.
let array_values = [1, 3, 3, 4, 5, 6, 6, 6,8, 4, 1]
let unique_values = [...new Set(array_values )];
console.log(unique_values );
// [1,3, 4, 5, 6, 8]5. Swapping Variables
This one-liner elegantly swaps the values of two variables. It leverages array destructuring to achieve a simple and readable swap operation.
// longhand
let a = 10;
let b = 20;
// Swapping variables using a temporary variable
let temp = a;
a = b;
b = temp;
console.log(a, b); // Output: 20 10
// shorthand
let a = 10;
let b = 20;
[a, b] = [b, a];
console.log(a, b); // Output: 20 106.Shuffling an Array
A quick way to shuffle the elements of an array.
const array = [23,3,34,3454,5,435,4343,33,343,3];
const shuffledArray = array.sort(() => Math.random() - 0.5); // [ 435, 23, 3454, 3, 33, 5, 3, 343, 34, 4343 ]
// you may get a different shuffle from mine because it is made randomly
7.Optional Chaining (Nullish Coalescing Operator)
Safely access nested properties without worrying about null or undefined.
const value = obj?.prop ?? 'default';8. Using Function.prototype.bind()
this is a method available on all JavaScript functions. It allows you to create a new function with a fixed this value and possibly pre-set arguments
const module = {
x: 42,
getX: function () {
return this.x;
},
};
const unboundGetX = module.getX;
console.log(unboundGetX()); // The function gets invoked at the global scope
// Expected output: undefined
const boundGetX = unboundGetX.bind(module);
console.log(boundGetX());
// Expected output: 42Partial Function Application
const add = function(a, b) {
return a + b;
};
const add2 = add.bind(null, 2);
const result = add2(3); // Output: 5Partially apply functions for more flexible code. In this example, add2 is a new function that always adds 2 to its argument.
9.Detecting the Environment (Browser or Node.js)
const isBrowser = typeof window !== 'undefined';
const isNode = typeof process !== 'undefined' && process.versions && process.versions.node;10. Currying Functions
Currying is a functional programming technique that allows you to transform a function with multiple arguments into a sequence of functions, each taking a single argument. This can make functions more flexible and composable.
code examples:
Example 1: Basic Currying
const add = (a) => (b) => a + b;
const add2 = add(2);
const result = add2(3); // Output: 5In this example, we have a add function that takes one argument a and returns a function that takes another argument b. This inner function adds a and b. When add(2) is called, it returns a new function add2 which adds 2 to any value passed to it.
Example 2: Currying with Multiple Arguments
const multiply = (a) => (b) => (c) => a * b * c;
const multiplyByTwo = multiply(2);
const multiplyByTwoAndThree = multiplyByTwo(3);
const result = multiplyByTwoAndThree(4); // Output: 24Example 3: Real-world Use Case (Formatting Dates)
const formatDate = (format) => (date) => {
const months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
const day = date.getDate();
const month = months[date.getMonth()];
const year = date.getFullYear();
switch (format) {
case 'dd-mm-yyyy':
return `${day}-${month}-${year}`;
case 'mm-dd-yyyy':
return `${month}-${day}-${year}`;
case 'yyyy-mm-dd':
return `${year}-${month}-${day}`;
default:
return 'Invalid format';
}
};
const formatAsDdMmYyyy = formatDate('dd-mm-yyyy');
const formattedDate = formatAsDdMmYyyy(new Date()); // e.g., Output: '07-Nov-2023'
In this example, formatDate is a curried function that takes a format argument and returns a function that takes a date argument. It formats the date based on the provided format. This allows for easy reuse of the formatting function with different formats.
11. Promise.all() for Parallel Execution
Using Promise.all() for parallel execution is a technique in JavaScript that allows you to concurrently run multiple asynchronous tasks and handle their results collectively. This is particularly useful when you have a set of independent asynchronous operations that can be executed simultaneously for improved performance.
const fetchUserData = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
const user = { id: 1, name: 'John Doe' };
resolve(user);
}, 2000); // Simulating an asynchronous operation
});
};
const fetchPosts = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
const posts = [{ id: 1, title: 'Post 1' }, { id: 2, title: 'Post 2' }];
resolve(posts);
}, 1500); // Simulating an asynchronous operation
});
};
const fetchComments = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
const comments = [{ id: 1, text: 'Comment 1' }, { id: 2, text: 'Comment 2' }];
resolve(comments);
}, 1000); // Simulating an asynchronous operation
});
};
Promise.all([fetchUserData(), fetchPosts(), fetchComments()])
.then(([userData, posts, comments]) => {
console.log('User Data:', userData);
console.log('Posts:', posts);
console.log('Comments:', comments);
})
.catch(error => {
console.error('Error:', error);
});conclusion
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