javascript_code_snippets.md

• 1. Check if a variable is an array:

function isArray(variable) {
  return Array.isArray(variable);
}

console.log(isArray([])); // Output: true
console.log(isArray('Hello')); // Output: false

• 2. Check if a variable is an object:

function isObject(variable) {
  return typeof variable === 'object' && variable !== null && !Array.isArray(variable);
}

console.log(isObject({})); // Output: true
console.log(isObject([])); // Output: false

• 3. Check if a variable is a function:

function isFunction(variable) {
  return typeof variable === 'function';
}

console.log(isFunction(() => {})); // Output: true
console.log(isFunction('Hello')); // Output: false

• 4. Convert a string to an integer:

var number = parseInt('42');

console.log(number); // Output: 42

• 5. Convert a string to a floating-point number:

var number = parseFloat('3.14');

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

• 6. Round a number to a specified decimal place:

var roundedNumber = 3.14159.toFixed(2);

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

• 7. Generate a random number between a specified range:

function getRandomNumber(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

console.log(getRandomNumber(1, 10)); // Output: Random number between 1 and 10

• 8. Get the current date:

var currentDate = new Date();

console.log(currentDate); // Output: Current date and time

• 9. Get the current year:

var currentYear = new Date().getFullYear();

console.log(currentYear); // Output: Current year

• 10. Get the current month:

var currentMonth = new Date().getMonth() + 1; // Month is zero-based

console.log(currentMonth); // Output: Current month (1-12)

• 11. Get the current day:

var currentDay = new Date().getDate();

console.log(currentDay); // Output: Current day (1-31)

• 12. Get the current time:

var currentTime = new Date().toLocaleTimeString();

console.log(currentTime); // Output: Current time

• 13. Get the length of an array:

var arr = [1, 2, 3];
var length = arr.length;

console.log(length); // Output: 3

• 14. Check if an array contains a specific element:

var arr = [1, 2, 3];
var containsElement = arr.includes(2);

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

• 15. Add an element to the end of an array:

var arr = [1, 2, 3];
arr.push(4);

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

• 16. Remove the last element from an array:

var arr = [1, 2, 3];
arr.pop();

console.log(arr); // Output: [1, 2]

• 17. Add an element to the beginning of an array:

var arr = [2, 3, 4];
arr.unshift(1);

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

• 18. Remove the first element from an array:

var arr = [1, 2, 3];
arr.shift();

console.log(arr); // Output: [2, 3]

• 19. Concatenate two arrays:

var arr1 = [1, 2];
var arr2 = [3, 4];
var concatenatedArray = arr1.concat(arr2);

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

• 20. Reverse the elements of an array:

var arr = [1, 2, 3];
arr.reverse();

console.log(arr); // Output: [3, 2, 1]

• 21. Sort the elements of an array in ascending order:

var arr = [3, 1, 2];
arr.sort();

console.log(arr); // Output: [1, 2, 3]

• 22. Sort the elements of an array in descending order:

var arr = [3, 1, 2];
arr.sort(function(a, b) {
  return b - a;
});

console.log(arr); // Output: [3, 2, 1]

• 23. Find the index of an element in an array:

var arr = [1, 2, 3];
var index = arr.indexOf(2);

console.log(index); // Output: 1

• 24. Remove an element from an array by index:

var arr = [1, 2, 3];
arr.splice(1, 1);

console.log(arr); // Output: [1, 3]

• 25. Copy an array:

var arr1 = [1, 2, 3];
var arr2 = arr1.slice();

console.log(arr2); // Output: [1, 2, 3]

• 26. Iterate over an array using a for loop:

var arr = [1, 2, 3];
for (var i = 0; i < arr.length; i++) {
  console.log(arr[i]);
}

• 27. Iterate over an array using forEach:

var arr = [1, 2, 3];
arr.forEach(function(element) {
  console.log(element);
});

• 28. Iterate over the keys of an object using for...in loop:

var obj = { name: 'John', age: 30 };
for (var key in obj) {
  console.log(key + ': ' + obj[key]);
}

• 29. Iterate over the values of an array using for...of loop:

var arr = [1, 2, 3];
for (var value of arr) {
  console.log(value);
}

• 30. Create a new array with the results of applying a function to each element:

var arr = [1, 2, 3];
var multipliedArray = arr.map(function(element) {
  return element * 2;
});

console.log(multipliedArray); // Output: [2, 4, 6]

• 31. Filter elements of an array based on a condition:

var arr = [1, 2, 3, 4, 5];
var filteredArray = arr.filter(function(element) {
  return element % 2 === 0;
});

console.log(filteredArray); // Output: [2, 4]

• 32. Check if all elements in an array satisfy a condition:

var arr = [2, 4, 6];
var allEven = arr.every(function(element) {
  return element % 2 === 0;
});

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

• 33. Check if at least one element in an array satisfies a condition:

var arr = [1, 2, 3];
var hasEven = arr.some(function(element) {
  return element % 2 === 0;
});

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

• 34. Reduce an array to a single value:

var arr = [1, 2, 3];
var sum = arr.reduce(function(accumulator, currentValue) {
  return accumulator + currentValue;
}, 0);

console.log(sum); // Output: 6

• 35. Find the maximum value in an array:

var arr = [3, 1, 2];
var max = Math.max(...arr);

console.log(max); // Output: 3

• 36. Find the minimum value in an array:

var arr = [3, 1, 2];
var min = Math.min(...arr);

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

• 37. Convert an array to a string, separating the elements with a delimiter:

var arr = [1, 2, 3];
var str = arr.join(', ');

console.log(str); // Output: "1, 2, 3"

• 38. Check if a string contains a substring:

var str = 'Hello, world!';
var containsSubstring = str.includes('world');

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

• 39. Check if a string starts with a specific prefix:

var str = 'Hello, world!';
var startsWithHello = str.startsWith('Hello');

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

• 40. Check if a string ends with a specific suffix:

var str = 'Hello, world!';
var endsWithWorld = str.endsWith('world!');

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

• 41. Convert a string to uppercase:

var str = 'hello';
var uppercaseStr = str.toUpperCase();

console.log(uppercaseStr); // Output: "HELLO"

• 42. Convert a string to lowercase:

var str = 'WORLD';
var lowercaseStr = str.toLowerCase();

console.log(lowercaseStr); // Output: "world"

• 43. Get the length of a string:

var str = 'Hello, world!';
var length = str.length;

console.log(length); // Output: 13

• 44. Replace all occurrences of a substring in a string:

var str = 'Hello, world!';
var replacedStr = str.replace('world', 'there');

console.log(replacedStr); // Output: "Hello, there!"

• 45. Remove leading and trailing whitespace from a string:

var str = '   Hello, world!   ';
var trimmedStr = str.trim();

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

• 46. Check if a number is an integer:

var number = 42;
var isInteger = Number.isInteger(number);

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

• 47. Check if a number is finite (not NaN or Infinity):

var number = 42;
var isFiniteNumber = isFinite(number);

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

• 48. Check if a number is NaN (Not-a-Number):

var number = NaN;
var isNaNNumber = isNaN(number);

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

• 49. Generate a random integer between a specified range (inclusive):

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

console.log(getRandomInt(1, 10)); // Output: Random number between 1 and 10

• 50. Get the absolute value of a number:

var number = -42;
var absoluteValue = Math.abs(number);

console.log(absoluteValue); // Output: 42

• 51. Round a number to the nearest integer:

var number = 3.7;
var roundedNumber = Math.round(number);

console.log(roundedNumber); // Output: 4

• 52. Generate a random hexadecimal color:

function getRandomHexColor() {
  var letters = '0123456789ABCDEF';
  var color = '#';
  for (var i = 0; i < 6; i++) {
    color += letters[Math.floor(Math.random() * 16)];
  }
  return color;
}

console.log(getRandomHexColor()); // Output: Random hexadecimal color

• 53. Get the current URL:

var currentURL = window.location.href;

console.log(currentURL); // Output: Current URL

• 54. Redirect to a different URL:

window.location.href = 'https://www.example.com';

• 55. Delay execution of code by a specified time (in milliseconds):

function delay(milliseconds) {
  return new Promise(function(resolve) {
    setTimeout(resolve, milliseconds);
  });
}

delay(2000).then(function() {
  console.log('Delayed code execution');
});

• 56. Create a new object with specified properties and values:

var obj = {
  name: 'John',
  age: 30
};

console.log(obj); // Output: { name: 'John', age: 30 }

• 57. Access the value of a property in an object:

var obj = {
  name: 'John',
  age: 30
};

console.log(obj.name); // Output: "John"

• 58. Set the value of a property in an object:

var obj = {
  name: 'John',
  age: 30
};

obj.name = 'Jane';

console.log(obj.name); // Output: "Jane"

• 59. Check if an object has a specific property:

var obj = {
  name: 'John',
  age: 30
};

var hasProperty = 'name' in obj;

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

• 60. Delete a property from an object:

var obj = {
  name: 'John',
  age: 30
};

delete obj.age;

console.log(obj); // Output: { name: 'John' }

• 61. Clone an object:

var obj1 = { name: 'John' };
var obj2 = { ...obj1 };

console.log(obj2); // Output: { name: 'John' }

• 62. Merge two objects into a new object:

var obj1 = { name: 'John' };
var obj2 = { age: 30 };
var mergedObj = { ...obj1, ...obj2 };

console.log(mergedObj); // Output: { name: 'John', age: 30 }

• 63. Create a new class (constructor function) in JavaScript:

function Person(name, age) {
  this.name = name;
  this.age = age;
}

var person = new Person('John', 30);

console.log(person.name); // Output: "John"
console.log(person.age); // Output: 30

• 64. Add a method to a class (constructor function):

function Person(name, age) {
  this.name = name;
  this.age = age;
  this.greet = function() {
    console.log('Hello, my name is ' + this.name);
  };
}

var person = new Person('John', 30);
person.greet(); // Output: "Hello, my name is John"

• 65. Inherit properties and methods from a parent class:

function Animal(name) {
  this.name = name;
}

Animal.prototype.greet = function() {
  console.log('Hello, my name is ' + this.name);
};

function Dog(name, breed) {
  Animal.call(this, name);
  this.breed = breed;
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;

var dog = new Dog('Buddy', 'Labrador');
dog.greet(); // Output: "Hello, my name is Buddy"

• 66. Use a try...catch block to handle exceptions:

try {
  // Code that might throw an exception
  throw new Error('Something went wrong');
} catch (error) {
  console.log(error.message);
}

• 67. Execute a function repeatedly at a specified interval (milliseconds):

function repeat(func, interval) {
  setInterval(func, interval);
}

function greet() {
  console.log('Hello');
}

repeat(greet, 1000); // Output: "Hello" every second

• 68. Convert an object to JSON string:

var obj = { name: 'John', age: 30 };
var jsonString = JSON.stringify(obj);

console.log(jsonString); // Output: "{"name":"John","age":30}"

• 69. Convert a JSON string to an object:

var jsonString = '{"name":"John","age":30}';
var obj = JSON.parse(jsonString);

console.log(obj.name); // Output: "John"
console.log(obj.age); // Output: 30

• 70. Check if a variable is defined (not undefined):

var variable;
var isDefined = typeof variable !== 'undefined';

console.log(isDefined); // Output: false

• 71. Check if a variable has a value (not null or undefined):

var variable = null;
var hasValue = variable !== null && typeof variable !== 'undefined';

console.log(hasValue); // Output: false

• 72. Check if a variable is a number:

var variable = 42;
var isNumber = typeof variable === 'number';

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

• 73. Check if a variable is a string:

var variable = 'Hello';
var isString = typeof variable === 'string';

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

• 74. Check if a variable is a boolean:

var variable = true;
var isBoolean = typeof variable === 'boolean';

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

• 75. Check if a variable is an object:

var variable = { name: 'John' };
var isObject = typeof variable === 'object' && variable !== null;

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

• 76. Check if a variable is a function:

var variable = function() {};
var isFunction = typeof variable === 'function';

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

• 77. Check if a variable is an array:

var variable = [1, 2, 3];
var isArray = Array.isArray(variable);

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

• 78. Check if a variable is a date:

var variable = new Date();
var isDate = variable instanceof Date;

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

• 79. Check if a variable is NaN (Not-a-Number):

var variable = NaN;
var isNaNNumber = Number.isNaN(variable);

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

• 80. Check if a variable is a finite number (not NaN or Infinity):

var variable = 42;
var isFiniteNumber = Number.isFinite(variable);

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

• 81. Get the current timestamp (milliseconds since January 1, 1970):

var timestamp = Date.now();

console.log(timestamp); // Output: Current timestamp

• 82. Format a number with commas as thousands separators:

var number = 1000000;
var formattedNumber = number.toLocaleString();

console.log(formattedNumber); // Output: "1,000,000"

• 83. Get the current screen width and height:

var screenWidth = window.innerWidth;
var screenHeight = window.innerHeight;

console.log(screenWidth); // Output: Current screen width
console.log(screenHeight); // Output: Current screen height

• 84. Detect the user's browser name and version:

var browserName = navigator.userAgent;
var browserVersion = navigator.appVersion;

console.log(browserName); // Output: User's browser name
console.log(browserVersion); // Output: User's browser version

• 85. Detect the user's operating system:

var operatingSystem = navigator.platform;

console.log(operatingSystem); // Output: User's operating system

• 86. Detect if the user is using a mobile device:

var isMobile = /Mobi|Android/i.test(navigator.userAgent);

console.log(isMobile); // Output: true or false

• 87. Encode a URL component:

var url = 'https://www.example.com/?name=John Doe';
var encodedURL = encodeURIComponent(url);

console.log(encodedURL); // Output: "https%3A%2F%2Fwww.example.com%2F%3Fname%3DJohn%20Doe"

• 88. Decode a URL component:

var encodedURL = 'https%3A%2F%2Fwww.example.com%2F%3Fname%3DJohn%20Doe';
var decodedURL = decodeURIComponent(encodedURL);

console.log(decodedURL); // Output: "https://www.example.com/?name=John Doe"

• 89. Get the value of a query parameter from the URL:

var url = 'https://www.example.com/?name=John&age=30';
var searchParams = new URLSearchParams(new URL(url).search);
var name = searchParams.get('name');

console.log(name); // Output: "John"

• 90. Get the current page scroll position:

var scrollX = window.pageXOffset;
var scrollY = window.pageYOffset;

console.log(scrollX); // Output: Current horizontal scroll position
console.log(scrollY); // Output: Current vertical scroll position

• 91. Scroll to a specific position on the page:

window.scrollTo({
  top: 0,
  behavior: 'smooth'
});

• 92. Detect if the user has scrolled to the bottom of the page:

window.addEventListener('scroll', function() {
  if (window.innerHeight + window.pageYOffset >= document.body.offsetHeight) {
    console.log('Reached the bottom of the page');
  }
});

• 93. Detect if the user has pressed a specific keyboard key:

window.addEventListener('keydown', function(event) {
  if (event.key === 'Enter') {
    console.log('Enter key pressed');
  }
});

• 94. Detect if the user has clicked on an element:

var element = document.getElementById('myButton');
element.addEventListener('click', function() {
  console.log('Button clicked');
});

• 95. Add a CSS class to an element:

var element = document.getElementById('myElement');
element.classList.add('myClass');

• 96. Remove a CSS class from an element:

var element = document.getElementById('myElement');
element.classList.remove('myClass');

• 97. Toggle a CSS class on an element:

var element = document.getElementById('myElement');
element.classList.toggle('myClass');

• 98. Create a new HTML element dynamically:

var newElement = document.createElement('div');
newElement.textContent = 'Hello, world!';
document.body.appendChild(newElement);

• 99. Remove an HTML element from the document:

var element = document.getElementById('myElement');
element.remove();

• 100. Execute a function when the DOM content has finished loading:

document.addEventListener('DOMContentLoaded', function() {
  console.log('DOM content loaded');
});

Thank you for reading. Follow me on twitter