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JavaScript Examples: Best JavaScript Code, Exercises

JavaScript is a scripting or programming language that is used both on the client-side and server-side development, it is a high-level, often just-in-time compiled, and multi-paradigm language that allows you to make web pages interactive.

JavaScript Examples, Programs, and Codes

This section contains JavaScript examples from basic concepts to advanced. Practice these examples to make a webpage interactive. Each example has the solved code, output, and explanation.

List of JavaScript Examples

1. Input value from the user using prompt
2. How to add float numbers using JavaScript?
3. How to Round off a number to next multiple of 5 using JavaScript?
4. Example of if with else
5. Example of if else if
6. Example of Nested if
7. Find largest of three numbers using Nested if in JavaScript
8. Example of Ternary Operator
9. Image Recognition Game using JavaScript
10. Code to input age and check person is eligible for voting or not
11. Function with default value
12. Function call example with given number of arguments and less arguments
13. Demonstrate the example of call by value in function
14. Some of the examples of user-defined functions
15. Common properties and methods of Array
16. Code to declare an array and assign the elements using array indexing
17. Code to declare an array and print using for each loop
18. Code to declare an array and print using for loop
19. Password strength checker in JavaScript
20. Print characters of a string in multiples of N in JavaScript
21. How to check whether a string contains a substring in JavaScript?
22. How to break in nested loops in JavaScript?
23. Understanding callbacks in JavaScript
24. How to create accordions with JavaScript?
25. JavaScript code to check number is Perfect or not
26. JavaScript code to check number is Armstrong or not
27. JavaScript code to check whether a Number is Prime or Not
28. JavaScript code to find largest of three numbers
29. Check number is palindrome or not in JavaScript
30. Form validation using JavaScript
31. JavaScript code to design calculator
32. Disable right click on webpage with JavaScript
33. How to make the font bold using JavaScript?
34. Return multiple elements from function in JavaScript
35. How to get URL parameters using JavaScript?
36. How to copy text to clipboard with JavaScript?
37. How to get days of current month in JavaScript?
38. Get browser details through JavaScript
39. Calculate the average of arguments in JavaScript
40. Ways to access object property in JavaScript
41. Count occurrence of a particular character in a string in JavaScript
42. Creating a property on prototype in JavaScript
43. Create a student object and print the details in JavaScript
44. Create a forward and back buttons in JavaScript
45. Different ways to create an Object in JavaScript
46. How to allow only alphabets in input field in JavaScript?
47. Get the size of a file with JavaScript
48. How to get the decimal part of a floating number in JavaScript?
49. Get current date, month and year in JavaScript
50. How to parse number from string in JavaScript?
51. How to find absolute value of a number in JavaScript?
52. Create functions with default arguments in JavaScript
53. How to return object from function in JavaScript?
54. Get index of an element in JavaScript
55. Print a fibonacci series in JavaScript
56. Find the larger of two numbers in JavaScript
57. Convert a number into different base in JavaScript
58. Find substring within a string in JavaScript
59. Count the number of arguments passed to function in JavaScript
60. Ways to create Date object in JavaScript
61. Check if number is a valid number in JavaScript
62. Determine the largest element in the array in JavaScript
63. Addition of two numbers using JavaScript
64. Create a user defined array in JavaScript
65. Concatenation operator in JavaScript
66. New variable declaration keywords in JavaScript
67. Dynamically add CSS class with JavaScript
68. Reverse an array in JavaScript
69. Access global variables inside function in JavaScript
70. How to fill dropdowns using JavaScript?
71. Create a string parser with symbols for actions in JavaScript
72. Join elements of an array in JavaScript
73. JavaScript multiply every array element with a constant
74. JavaScript check if an array element is empty
75. Different ways to display output in JavaScript
76. Check if an element is present in an Array in JavaScript?
77. How to change the font-size with JavaScript?
78. JavaScript Reverse print an array
79. Template literals in JavaScript
80. How to get the extension of a file using JavaScript?
81. The JavaScript forEach method in detail
82. Generate random number within a range in JavaScript
83. JavaScript program to create an object from a function
84. JavaScript program to split the keywords in the string
85. JavaScript program to check if the variable is a valid string variable
86. JavaScript Program to print sum of range with steps
87. JavaScript Program to create a power function and print the result
88. JavaScript to detect whether page is load on Mobile or Desktop
89. JavaScript - Select/Unselect (Check/Uncheck) all CheckBoxes on Button Click
90. JavaScript - Allow only numbers in TextBox (Restrict Alphabets and Special Characters)
91. JavaScript - Redirect to another URL on Button Click
92. JavaScript - Display Input Text into Lowercase
93. JavaScript - Display Input Text into Uppercase
94. JavaScript - Display current Date and Time
95. Check selected Radio Button value using JavaScript
96. JavaScript function to add two integer numbers
97. Show/Hide Div on Button Click using JavaScript
98. Display different Alert Message on different Button Click Event using JavaScript
99. Display Alert Message on Button Click Event using JavaScript
100. JavaScript - Print value of all checked (selected) CheckBoxes on Button click
101. JavaScript - Print Selected Item from SelectBox
102. JavaScript - Add user entered item into ListBox
103. JavaScript - Required Field Validator for TextBox on Submit
104. JavaScript - Move Object with Arrow Keys using JavaScript Function
105. JavaScript - Set Focus on Particular Field in a Form using JavaScript Function
106. JavaScript - Set Customize Text in Browser Status Bar using JavaScript Function
107. JavaScript - Detect and Display Screen Resolution using JavaScript Function
108. JavaScript - Function to Refresh Page on Button Click
109. JavaScript - Function to Display Table of an entered Number
110. JavaScript - Disable Button after Click using JavaScript Function
111. JavaScript - Close Current Tab on Button Click with Confirmation
112. JavaScript - Show/Hide Paragraph Text inside Div on Button Click
113. Simple Web Dictionary | JavaScript Switch Statement Project
114. Data Unit Conversion Tool in JavaScript
115. Age calculator Web Application | Integrating JavaScript function with form
116. Lowercase to Uppercase Converter JavaScript Tool | Web App Project
117. Sample report card web application prototype using JavaScript
118. JavaScript | Create an object and display its values in a table
119. JavaScript | Create an object and display its content in a table through JavaScript function
120. JavaScript | Create an object by passing values in the function and display in the table
121. Capitalize words in a string in JavaScript
122. How to get multiple random unique elements from an array in JavaScript?
123. JavaScript - How to get a key in an object by its value?
124. JavaScript - How to get the first key name of a JavaScript Object?
125. JavaScript - How to check if a key exists in a JavaScript Object?
126. JavaScript - How to iterate over a JavaScript Object?
127. How to access an object having spaces in the object's key using JavaScript?
128. How to check if an array includes an object in JavaScript?
129. Convert an array to an object in JavaScript
130. How to check if a JavaScript object is a DOM object?
131. How to check object is an array in JavaScript?
132. Search from Array of Objects | JavaScript
133. How to replace element from an array in JavaScript?
134. Web Application: A To-do List using JavaScript
135. How to add a class name to an element in JavaScript?
136. How to change the src of an element in JavaScript?
137. How to change the class of an element in JavaScript?
138. How to create hash from string in JavaScript?
139. How to remove CSS property using JavaScript?
140. How to round Off a number upto 2 decimal places using JavaScript?
141. How to return a value from a JS asynchronous callback function?
142. How to compare two JavaScript array objects using JavaScript?
143. Method to show or hide elements in HTML using display property in JavaScript
144. Get current time in Hours24: Minutes: Seconds format in JavaScript
145. Get current Date in Date / Month / Year format in JavaScript
146. Get current UTC time in Hours24: Minutes: Seconds format in JavaScript
147. Get current UTC Date in Date / Month / Year format in JavaScript
148. Retrieve the position (XY) of an HTML element
149. Dynamically Populating drop-down list from selection another drop-down value
150. How can I merge properties of two JavaScript objects dynamically?
151. Length of a JavaScript object
152. JavaScript: How to append something to an array?
153. Is there a standard function to check for null, undefined, or blank variables in JavaScript?
154. How to replace all occurrences of a string in JavaScript?
155. How do I check if an array includes a value in JavaScript?
156. How do you get a timestamp in JavaScript?
157. Which 'href' value should I use for JavaScript links, '#' or 'javascript:void(0)'?
158. What is the !! (not not) operator in JavaScript?
159. What does 'use strict' do in JavaScript, and what is the reasoning behind it?
160. What is the most efficient way to deep clone an object in JavaScript?
161. How do I remove a property from a JavaScript object?
162. Check whether a string contains a substring using includes() and indexOf() methods in JavaScript
163. How can I remove a specific item from an array in JavaScript?
164. var functionName = function() {} vs function functionName() {}
165. What's the difference between using 'let' and 'var'?
166. Which equals operator (== vs ===) should be used in JavaScript comparisons?
167. Check if a variable is a string in JavaScript
168. Can (a== 1 && a ==2 && a==3) ever evaluate to true?
169. Open a URL in a new tab (and not a new window)
170. Compare two dates with JavaScript
171. Set a default parameter value for a JavaScript function
172. Validate decimal numbers in JavaScript - IsNumeric()
173. How can I determine if a variable is 'undefined' or 'null'?
174. Generate random string/characters in JavaScript
175. How to check if element is visible after scrolling?
176. Get all unique values in a JavaScript array (remove duplicates)
177. JavaScript equivalent to printf/String.Format
178. How to find the sum of an array of numbers?
179. Replace multiple characters in one replace call using JavaScript
180. How to print a number with commas as thousands separators in JavaScript?
181. Can I get the name of the currently running function in JavaScript?
182. What is the opposite of event.preventDefault() in JavaScript?
183. JavaScript - Add st, nd, rd and th (ordinal) suffix to a number
184. How can I find the length of a number in JavaScript?
185. How do I redirect to another webpage using JavaScript?
186. How do I refresh a page using JavaScript?
187. How to link a JavaScript file to a HTML file?
188. HTML text input allow only numeric input JavaScript
189. Get selected element's outer HTML using JavaScript
190. How to check for a #hash in a URL using JavaScript?
191. Remove all whitespace from a string in JavaScript
192. Regex to replace multiple spaces with a single space in JavaScript
193. How to get image size (height and width) using JavaScript?
194. Run JavaScript function when user finishes typing instead of on key up?
195. Commonly Accepted Best Practices Around Code Organization in JavaScript
196. How to check the user is using Internet Explorer using JavaScript?
197. How to select and highlight a text within an element using JavaScript?
198. How to check if an array is empty or exists using JavaScript?
199. How to check if the URL contains a given string using JavaScript?
200. How to add or update a query string parameter using JavaScript?
201. How to create a bold text using JavaScript?
202. How to get selected text from a textbox using JavaScript?
203. How to insert text into the textarea at the current cursor position?
204. How to delete the first word from a string using JavaScript?
205. How to select all text in HTML text input when clicked using JavaScript?
206. JavaScript - Shortening an array
207. JavaScript - Create an empty array of fixed length
208. JavaScript - Array with non-writable length
209. How to get the last element of an array in JavaScript?
210. How to concatenate two arrays in JavaScript?
211. How to concatenate three arrays in JavaScript?
212. How to concatenate values to an array in JavaScript?
213. How to concatenate nested JavaScript arrays?
214. How to concatenate array-like objects in JavaScript?
215. JavaScript - Using concat() on sparse arrays
216. How to find the sum of a nested array in JavaScript?
217. How to find the largest numbers from each subarray in JavaScript?
218. JavaScript - Iterating an array with index and element
219. How to check a condition with all array elements in JavaScript?
220. How to create a matrix of all ones in JavaScript?
221. How to populate an empty array in JavaScript?
222. JavaScript - Filter invalid entries from JSON
223. How to parse float with two decimal places in JavaScript?
224. How to parse JSON object using JSON.stringify() in JavaScript?
225. How to convert an array into an object in JavaScript?