25 Handy Javascript Code Snippets for Everyday Use

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Table of Contents

Code Snippet 1 - Adding Two Numbers & Converting Strings to Numbers

Adding two numbers is one of the most basic operations in programming. In Javascript, you can easily achieve this using the "+" operator. Here's an example:

const num1 = 5;
const num2 = 10;
const sum = num1 + num2;

console.log(sum); // Output: 15

You can also add two numbers using the parseInt() function to convert strings to numbers:

const num1 = "5";
const num2 = "10";
const sum = parseInt(num1) + parseInt(num2);

console.log(sum); // Output: 15

Code Snippet 2 - Checking if a String Contains a Substring

Often, you need to check if a string contains a specific substring. Javascript provides the includes() method to accomplish this. Here's an example:

const str = "Hello, World!";
const substring = "World";
const containsSubstring = str.includes(substring);

console.log(containsSubstring); // Output: true

You can also use the indexOf() method to check if a string contains a substring. It returns the index of the first occurrence of the substring, or -1 if the substring is not found:

const str = "Hello, World!";
const substring = "World";
const containsSubstring = str.indexOf(substring) !== -1;

console.log(containsSubstring); // Output: true

Code Snippet 3 - Converting Strings to Numbers

In Javascript, you can convert strings to numbers using the parseInt() and parseFloat() functions. The parseInt() function converts a string to an integer, while the parseFloat() function converts a string to a floating-point number. Here's an example:

const str1 = "10";
const num1 = parseInt(str1);

console.log(num1); // Output: 10

const str2 = "3.14";
const num2 = parseFloat(str2);

console.log(num2); // Output: 3.14

Code Snippet 4 - Removing Duplicates from an Array

To remove duplicates from an array, you can use the filter() method along with the indexOf() method. Here's an example:

const array = [1, 2, 3, 2, 4, 5, 1, 3];
const uniqueArray = array.filter((value, index, self) =&gt; {
  return self.indexOf(value) === index;
});

console.log(uniqueArray); // Output: [1, 2, 3, 4, 5]

Alternatively, you can use the Set object to remove duplicates from an array:

const array = [1, 2, 3, 2, 4, 5, 1, 3];
const uniqueArray = [...new Set(array)];

console.log(uniqueArray); // Output: [1, 2, 3, 4, 5]

Code Snippet 5 - Checking if an Array Contains a Specific Value

To check if an array contains a specific value, you can use the includes() method. Here's an example:

const array = [1, 2, 3, 4, 5];
const value = 3;
const containsValue = array.includes(value);

console.log(containsValue); // Output: true

You can also use the indexOf() method to check if an array contains a specific value. It returns the index of the first occurrence of the value, or -1 if the value is not found:

const array = [1, 2, 3, 4, 5];
const value = 3;
const containsValue = array.indexOf(value) !== -1;

console.log(containsValue); // Output: true

Code Snippet 6 - Reversing a String

To reverse a string in Javascript, you can use the split(), reverse(), and join() methods. Here's an example:

const str = "Hello, World!";
const reversedStr = str.split("").reverse().join("");

console.log(reversedStr); // Output: "!dlroW ,olleH"

Code Snippet 7 - Finding the Maximum and Minimum Values in an Array

To find the maximum and minimum values in an array, you can use the Math.max() and Math.min() functions along with the spread operator. Here's an example:

const array = [1, 2, 3, 4, 5];
const max = Math.max(...array);
const min = Math.min(...array);

console.log(max); // Output: 5
console.log(min); // Output: 1

Code Snippet 8 - Sorting an Array in Ascending and Descending Order

To sort an array in ascending and descending order, you can use the sort() method along with a compare function. Here's an example:

const array = [3, 1, 4, 2, 5];
const ascendingOrder = array.sort((a, b) =&gt; a - b);
const descendingOrder = array.sort((a, b) =&gt; b - a);

console.log(ascendingOrder); // Output: [1, 2, 3, 4, 5]
console.log(descendingOrder); // Output: [5, 4, 3, 2, 1]

Code Snippet 9 - Checking if an Object is Empty

To check if an object is empty, you can use the Object.keys() method. If the length of the keys array is 0, then the object is empty. Here's an example:

const obj1 = {};
const obj2 = { name: "John", age: 30 };
const isEmpty1 = Object.keys(obj1).length === 0;
const isEmpty2 = Object.keys(obj2).length === 0;

console.log(isEmpty1); // Output: true
console.log(isEmpty2); // Output: false

Code Snippet 10 - Generating Random Numbers

To generate random numbers in Javascript, you can use the Math.random() function. Here's an example:

const randomNum = Math.random();

console.log(randomNum); // Output: a random number between 0 and 1

If you want to generate random numbers within a specific range, you can use the following formula:

const min = 1;
const max = 10;
const randomNumInRange = Math.floor(Math.random() * (max - min + 1)) + min;

console.log(randomNumInRange); // Output: a random number between 1 and 10

Code Snippet 11 - Capitalizing the First Letter of a String

To capitalize the first letter of a string in Javascript, you can use the charAt() and toUpperCase() methods. Here's an example:

const str = "hello, world!";
const capitalizedStr = str.charAt(0).toUpperCase() + str.slice(1);

console.log(capitalizedStr); // Output: "Hello, world!"

Code Snippet 12 - Finding the Length of an Object

To find the length of an object in Javascript, you can use the Object.keys() method. The length of the keys array represents the number of properties in the object. Here's an example:

const obj = { name: "John", age: 30 };
const length = Object.keys(obj).length;

console.log(length); // Output: 2

Code Snippet 13 - Checking if a Number is Even or Odd

To check if a number is even or odd in Javascript, you can use the modulo operator (%). If the number modulo 2 is 0, then it's even. Otherwise, it's odd. Here's an example:

const num = 7;
const isEven = num % 2 === 0;
const isOdd = num % 2 !== 0;

console.log(isEven); // Output: false
console.log(isOdd); // Output: true

Code Snippet 14 - Trimming Whitespace from a String

To trim whitespace from the beginning and end of a string in Javascript, you can use the trim() method. Here's an example:

const str = "  Hello, World!  ";
const trimmedStr = str.trim();

console.log(trimmedStr); // Output: "Hello, World!"

Code Snippet 15 - Converting a String to Title Case

To convert a string to title case in Javascript, you can use a combination of the split(), map(), and join() methods along with the charAt() and toUpperCase() methods. Here's an example:

const str = "hello, world!";
const titleCaseStr = str.split(" ").map(word =&gt; word.charAt(0).toUpperCase() + word.slice(1)).join(" ");

console.log(titleCaseStr); // Output: "Hello, World!"

Code Snippet 16 - Checking if a Year is a Leap Year

To check if a year is a leap year in Javascript, you can use the modulo operator (%) and logical operators. Here's an example:

const year = 2020;
const isLeapYear = (year % 4 === 0 &amp;&amp; year % 100 !== 0) || year % 400 === 0;

console.log(isLeapYear); // Output: true

Code Snippet 17 - Calculating the Factorial of a Number

To calculate the factorial of a number in Javascript, you can use a recursive function. Here's an example:

function factorial(num) {
  if (num === 0 || num === 1) {
    return 1;
  } else {
    return num * factorial(num - 1);
  }
}

const num = 5;
const factorialNum = factorial(num);

console.log(factorialNum); // Output: 120

Code Snippet 18 - Calculating the Fibonacci Sequence

To calculate the Fibonacci sequence in Javascript, you can use a recursive function. Here's an example:

function fibonacci(num) {
  if (num &lt;= 1) {
    return num;
  } else {
    return fibonacci(num - 1) + fibonacci(num - 2);
  }
}

const num = 6;
const fibonacciNum = fibonacci(num);

console.log(fibonacciNum); // Output: 8

Code Snippet 19 - Checking if a Number is Prime

To check if a number is prime in Javascript, you can use a for loop to iterate from 2 to the square root of the number. If the number is divisible by any of the values in this range, it's not prime. Here's an example:

function isPrime(num) {
  if (num &lt;= 1) {
    return false;
  }
  
  for (let i = 2; i &lt;= Math.sqrt(num); i++) {
    if (num % i === 0) {
      return false;
    }
  }
  
  return true;
}

const num = 17;
const isPrimeNum = isPrime(num);

console.log(isPrimeNum); // Output: true

Code Snippet 20 - Finding the Longest Word in a String

To find the longest word in a string in Javascript, you can use the split() method to convert the string into an array of words. Then, you can use the reduce() method to find the word with the maximum length. Here's an example:

const str = "The quick brown fox jumps over the lazy dog";
const longestWord = str.split(" ").reduce((prev, current) =&gt; (prev.length &gt; current.length) ? prev : current);

console.log(longestWord); // Output: "quick"

Code Snippet 21 - Reversing the Order of Words in a String

To reverse the order of words in a string in Javascript, you can use the split() and reverse() methods. Here's an example:

const str = "The quick brown fox";
const reversedStr = str.split(" ").reverse().join(" ");

console.log(reversedStr); // Output: "fox brown quick The"

Code Snippet 22 - Converting a Number to Roman Numerals

To convert a number to Roman numerals in Javascript, you can use a combination of if-else statements and a lookup table. Here's an example:

function convertToRoman(num) {
  const romanNumerals = {
    1000: "M",
    900: "CM",
    500: "D",
    400: "CD",
    100: "C",
    90: "XC",
    50: "L",
    40: "XL",
    10: "X",
    9: "IX",
    5: "V",
    4: "IV",
    1: "I"
  };
  
  let result = "";
  
  for (let value in romanNumerals) {
    while (num &gt;= value) {
      result += romanNumerals[value];
      num -= value;
    }
  }
  
  return result;
}

const num = 36;
const romanNum = convertToRoman(num);

console.log(romanNum); // Output: "XXXVI"

Code Snippet 23 - Generating a Random Password

To generate a random password in Javascript, you can use a combination of string manipulation and random number generation. Here's an example:

function generateRandomPassword(length) {
  const characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&amp;*()";
  let password = "";
  
  for (let i = 0; i &lt; length; i++) {
    const randomIndex = Math.floor(Math.random() * characters.length);
    password += characters[randomIndex];
  }
  
  return password;
}

const passwordLength = 8;
const randomPassword = generateRandomPassword(passwordLength);

console.log(randomPassword); // Output: a randomly generated password

Code Snippet 24 - Checking if a String is Palindrome

To check if a string is a palindrome in Javascript, you can compare the string with its reversed version. Here's an example:

function isPalindrome(str) {
  const reversedStr = str.split("").reverse().join("");
  return str === reversedStr;
}

const str = "madam";
const isPalindromeStr = isPalindrome(str);

console.log(isPalindromeStr); // Output: true

Code Snippet 25 - Converting Temperature Units

To convert temperature units in Javascript, you can use the following formulas:

- Celsius to Fahrenheit: F = (C * 9/5) + 32

- Fahrenheit to Celsius: C = (F - 32) * 5/9

Here's an example:

function celsiusToFahrenheit(celsius) {
  return (celsius * 9/5) + 32;
}

function fahrenheitToCelsius(fahrenheit) {
  return (fahrenheit - 32) * 5/9;
}

const celsius = 25;
const fahrenheit = celsiusToFahrenheit(celsius);
console.log(fahrenheit); // Output: 77

const convertedCelsius = fahrenheitToCelsius(fahrenheit);
console.log(convertedCelsius); // Output: 25

External Sources

- MDN Web Docs: JavaScript

- W3Schools: JavaScript