1What are the possible ways to create objects in JavaScript
2What is a prototype chain
3What is the difference between Call, Apply and Bind
4What is JSON and its common operations
5What is the purpose of the array slice method
6What is the purpose of the array splice method
7What is the difference between slice and splice
8How do you compare Object and Map
9What is the difference between == and === operators
10What are lambda expressions or arrow functions
11What is a first class function
12What is a first order function
13What is a higher order function
14What is a unary function
15What is the currying function
16What is a pure function
17What is the purpose of the let keyword
18What is the difference between let and var
19What is the reason to choose the name let as a keyword
20How do you redeclare variables in a switch block without an error
21What is the Temporal Dead Zone
22What is an IIFE (Immediately Invoked Function Expression)
23How do you decode or encode a URL in JavaScript?
24What is memoization
25What is Hoisting
26What are classes in ES6
27What are closures
28What are modules
29Why do you need modules
30What is scope in javascript
31What is a service worker
32How do you manipulate DOM using a service worker
33How do you reuse information across service worker restarts
34What is IndexedDB
35What is web storage
36What is a post message
37What is a Cookie
38Why do you need a Cookie
39What are the options in a cookie
40How do you delete a cookie
41What are the differences between cookie, local storage and session storage
42What is the main difference between localStorage and sessionStorage
43How do you access web storage
44What are the methods available on session storage
45What is a storage event and its event handler
46Why do you need web storage
47How do you check web storage browser support
48How do you check web workers browser support
49Give an example of a web worker
50What are the restrictions of web workers on DOM
51What is a promise
52Why do you need a promise
53What are the three states of promise
54What is a callback function
55Why do we need callbacks
56What is a callback hell
57What are server-sent events
58How do you receive server-sent event notifications
59How do you check browser support for server-sent events
60What are the events available for server sent events
61What are the main rules of promise
62What is callback in callback
63What is promise chaining
64What is promise.all
65What is the purpose of the race method in promise
66What is a strict mode in javascript
67Why do you need strict mode
68How do you declare strict mode
69What is the purpose of double exclamation
70What is the purpose of the delete operator
71What is typeof operator
72What is undefined property
73What is null value
74What is the difference between null and undefined
75What is eval
76What is the difference between window and document
77How do you access history in javascript
78How do you detect caps lock key turned on or not
79What is isNaN
80What are the differences between undeclared and undefined variables
81What are global variables
82What are the problems with global variables
83What is NaN property
84What is the purpose of isFinite function
85What is an event flow
86What is event bubbling
87What is event capturing
88How do you submit a form using JavaScript
89How do you find operating system details
90What is the difference between document load and DOMContentLoaded events
91What is the difference between native, host and user objects
92What are the tools or techniques used for debugging JavaScript code
93What are the pros and cons of promises over callbacks
94What is the difference between an attribute and a property
95What is same-origin policy
96What is the purpose of void 0
97Is JavaScript a compiled or interpreted language
98Is JavaScript a case-sensitive language
99Is there any relation between Java and JavaScript
100What are events
101Who created javascript
102What is the use of preventDefault method
103What is the use of stopPropagation method
104What are the steps involved in return false usage
105What is BOM
106What is the use of setTimeout
107What is the use of setInterval
108Why is JavaScript treated as Single threaded
109What is an event delegation
110What is ECMAScript
111What is JSON
112What are the syntax rules of JSON
113What is the purpose JSON stringify
114How do you parse JSON string
115Why do you need JSON
116What are PWAs
117What is the purpose of clearTimeout method
118What is the purpose of clearInterval method
119How do you redirect new page in javascript
120How do you check whether a string contains a substring
121How do you validate an email in javascript
122How do you get the current url with javascript
123What are the various url properties of location object
124How do get query string values in javascript
125How do you check if a key exists in an object
126How do you loop through or enumerate javascript object
127How do you test for an empty object
128What is an arguments object
129How do you make first letter of the string in an uppercase
130What are the pros and cons of for loops
131How do you display the current date in javascript
132How do you compare two date objects
133How do you check if a string starts with another string
134How do you trim a string in javascript
135How do you add a key value pair in javascript
136Is the !– notation represents a special operator
137How do you assign default values to variables
138How do you define multiline strings
139What is an app shell model
140Can we define properties for functions
141What is the way to find the number of parameters expected by a function
142What is a polyfill
143What are break and continue statements
144What are js labels
145What are the benefits of keeping declarations at the top
146What are the benefits of initializing variables
147What are the recommendations to create new object
148How do you define JSON arrays
149How do you generate random integers
150Can you write a random integers function to print integers within a range
151What is tree shaking
152What is the need of tree shaking
153Is it recommended to use eval
154What is a Regular Expression
155What are the string methods that accept Regular expression
156What are modifiers in regular expression
157What are regular expression patterns
158What is a RegExp object
159How do you search a string for a pattern
160What is the purpose of exec method
161How do you change the style of a HTML element
162What would be the result of 1+2+’3′
163What is a debugger statement
164What is the purpose of breakpoints in debugging
165Can I use reserved words as identifiers
166How do you detect a mobile browser
167How do you detect a mobile browser without regexp
168How do you get the image width and height using JS
169How do you make synchronous HTTP request
170How do you make asynchronous HTTP request
171How do you convert date to another timezone in javascript
172What are the properties used to get size of window
173What is a conditional operator in javascript
174Can you apply chaining on conditional operator
175What are the ways to execute javascript after page load
176What is the difference between proto and prototype
177Can you give an example of when you really need a semicolon
178What is a freeze method
179What is the purpose of freeze method
180Why do I need to use freeze method
181How do you detect a browser language preference
182How to convert string to title case with javascript
183How do you detect javascript disabled in the page
184What are various operators supported by javascript
185What is a rest parameter
186What happens if you do not use rest parameter as a last argument
187What are the bitwise operators available in javascript
188What is a spread operator
189How do you determine whether object is frozen or not
190How do you determine two values same or not using object
191What is the purpose of using object is method
192How do you copy properties from one object to other
193What are the applications of assign method
194What is a proxy object
195What is the purpose of seal method
196What are the applications of seal method
197What are the differences between freeze and seal methods
198How do you determine if an object is sealed or not
199How do you get enumerable key and value pairs
200What is the main difference between Object.values and Object.entries method
201How can you get the list of keys of any object
202How do you create an object with prototype
203What is a WeakSet
204What are the differences between WeakSet and Set
205List down the collection of methods available on WeakSet
206What is a WeakMap
207What are the differences between WeakMap and Map
208List down the collection of methods available on WeakMap
209What is the purpose of uneval
210How do you encode an URL
211How do you decode an URL
212How do you print the contents of web page
213What is the difference between uneval and eval
214What is an anonymous function
215What is the precedence order between local and global variables
216What are javascript accessors
217How do you define property on Object constructor
218What is the difference between get and defineProperty
219What are the advantages of Getters and Setters
220Can I add getters and setters using defineProperty method
221What is the purpose of switch-case
222What are the conventions to be followed for the usage of switch case
223What are primitive data types
224What are the different ways to access object properties
225What are the function parameter rules
226What is an error object
227When you get a syntax error
228What are the different error names from error object
229What are the various statements in error handling
230What are the two types of loops in javascript
231What is nodejs
232What is an Intl object
233How do you perform language specific date and time formatting
234What is an Iterator
235How does synchronous iteration works
236What is an event loop
237What is call stack
238What is an event queue
239What is a decorator
240What are the properties of Intl object
241What is an Unary operator
242How do you sort elements in an array
243What is the purpose of compareFunction while sorting arrays
244How do you reversing an array
245How do you find min and max value in an array
246How do you find min and max values without Math functions
247What is an empty statement and purpose of it
248How do you get metadata of a module
249What is a comma operator
250What is the advantage of a comma operator
251What is typescript
252What are the differences between javascript and typescript
253What are the advantages of typescript over javascript
254What is an object initializer
255What is a constructor method
256What happens if you write constructor more than once in a class
257How do you call the constructor of a parent class
258How do you get the prototype of an object
259What happens If I pass string type for getPrototype method
260How do you set prototype of one object to another
261How do you check whether an object can be extendable or not
262How do you prevent an object to extend
263What are the different ways to make an object non-extensible
264How do you define multiple properties on an object
265What is MEAN in javascript
266What Is Obfuscation in javascript
267Why do you need Obfuscation
268What is Minification
269What are the advantages of minification
270What are the differences between Obfuscation and Encryption
271What are the common tools used for minification
272How do you perform form validation using javascript
273How do you perform form validation without javascript
274What are the DOM methods available for constraint validation
275What are the available constraint validation DOM properties
276What are the list of validity properties
277Give an example usage of rangeOverflow property
278Is enums feature available in javascript
279What is an enum
280How do you list all properties of an object
281How do you get property descriptors of an object
282What are the attributes provided by a property descriptor
283How do you extend classes
284How do I modify the url without reloading the page
285How do you check whether an array includes a particular value or not
286How do you compare scalar arrays
287How to get the value from get parameters
288How do you print numbers with commas as thousand separators
289What is the difference between java and javascript
290Does JavaScript supports namespace
291How do you declare namespace
292How do you invoke javascript code in an iframe from parent page
293How do get the timezone offset from date
294How do you load CSS and JS files dynamically
295What are the different methods to find HTML elements in DOM
296What is jQuery
297What is V8 JavaScript engine
298Why do we call javascript as dynamic language
299What is a void operator
300How to set the cursor to wait
301How do you create an infinite loop
302Why do you need to avoid with statement
303What is the output of the following for loops
304List down some of the features of ES6
305What is ES6
306Can I redeclare let and const variables
307Does the const variable make the value immutable
308What are default parameters
309What are template literals
310How do you write multi-line strings in template literals
311What are nesting templates
312What are tagged templates
313What are raw strings
314What is destructuring assignment
315What are default values in destructuring assignment
316How do you swap variables in destructuring assignment
317What are enhanced object literals
318What are dynamic imports
319What are the use cases for dynamic imports
320What are typed arrays
321What are the advantages of module loaders
322What is collation
323What is for…of statement
324What is the output of below spread operator array
325Is PostMessage secure
326What are the problems with postmessage target origin as wildcard
327How do you avoid receiving postMessages from attackers
328Can I avoid using postMessages completely
329Is postMessages synchronous
330What paradigm is Javascript
331What is the difference between internal and external javascript
332Is JavaScript faster than server side script
333How do you get the status of a checkbox
334What is the purpose of double tilde operator
335How do you convert character to ASCII code
336What is ArrayBuffer
337What is the output of below string expression
338What is the purpose of Error object
339What is the purpose of EvalError object
340What are the list of cases error thrown from non-strict mode to strict mode
341Do all objects have prototypes
342What is the difference between a parameter and an argument
343What is the purpose of some method in arrays
344How do you combine two or more arrays
345What is the difference between Shallow and Deep copy
346How do you create specific number of copies of a string
347How do you return all matching strings against a regular expression
348How do you trim a string at the beginning or ending
349What is the output of below console statement with unary operator
350Does javascript uses mixins
351What is a thunk function
352What are asynchronous thunks
353What is the output of below function calls
354How to remove all line breaks from a string
355What is the difference between reflow and repaint
356What happens with negating an array
357What happens if we add two arrays
358What is the output of prepend additive operator on falsy values
359How do you create self string using special characters
360How do you remove falsy values from an array
361How do you get unique values of an array
362What is destructuring aliases
363How do you map the array values without using map method
364How do you empty an array
365How do you round numbers to certain decimals
366What is the easiest way to convert an array to an object
367How do you create an array with some data
368What are the placeholders from console object
369Is it possible to add CSS to console messages
370What is the purpose of dir method of console object
371Is it possible to debug HTML elements in console
372How do you display data in a tabular format using console object
373How do you verify that an argument is a Number or not
374How do you create copy to clipboard button
375What is the shortcut to get timestamp
376How do you flattening multi dimensional arrays
377What is the easiest multi condition checking
378How do you capture browser back button
379How do you disable right click in the web page
380What are wrapper objects
381What is AJAX
382What are the different ways to deal with Asynchronous Code
383How to cancel a fetch request
384What is web speech API
385What is minimum timeout throttling
386How do you implement zero timeout in modern browsers
387What are tasks in event loop
388What is microtask
389What are different event loops
390What is the purpose of queueMicrotask
391How do you use javascript libraries in typescript file
392What are the differences between promises and observables
393What is heap
394What is an event table
395What is a microTask queue
396What is the difference between shim and polyfill
397How do you detect primitive or non primitive value type
398What is babel
399Is Node.js completely single threaded
400What are the common use cases of observables
401What is RxJS
402What is the difference between Function constructor and function declaration
403What is a Short circuit condition
404What is the easiest way to resize an array
405What is an observable
406What is the difference between function and class declarations
407What is an async function
408How do you prevent promises swallowing errors
409What is deno
410How do you make an object iterable in javascript
411What is a Proper Tail Call
412How do you check an object is a promise or not
413How to detect if a function is called as constructor
414What are the differences between arguments object and rest parameter
415What are the differences between spread operator and rest parameter
416What are the different kinds of generators
417What are the built-in iterables
418What are the differences between for…of and for…in statements
419How do you define instance and non-instance properties
420What is the difference between isNaN and Number.isNaN?
421How to invoke an IIFE without any extra brackets?
422Is that possible to use expressions in switch cases?
423What is the easiest way to ignore promise errors?
424How do style the console output using CSS?
425What is nullish coalescing operator (??)?
426How do you group and nest console output?
427What is the difference between dense and sparse arrays?
428What are the different ways to create sparse arrays?
429What is the difference between setTimeout, setImmediate and process.nextTick?
430How do you reverse an array without modifying original array?
431How do you create custom HTML element?
432What is global execution context?
433What is function execution context?
434What is debouncing?
435What is throttling?
436What is optional chaining?
437What is an environment record?
438How to verify if a variable is an array?
439What is pass by value and pass by reference?
440What are the differences between primitives and non-primitives?
441How do you create your own bind method using either call or apply method?
442What are the differences between pure and impure functions?
443What is referential transparency?
444What are the possible side-effects in javascript?
445What are compose and pipe functions?
446What is module pattern?
447What is Function Composition?
448How to use await outside of async function prior to ES2022?
449What is the purpose of the this keyword in JavaScript?
450What are the uses of closures?
451What are the phases of execution context?
452What are the possible reasons for memory leaks?
453What are the optimization techniques of V8 engine?
454What are the examples of built-in higher order functions?
455What are the benefits higher order functions?
456How do you create polyfills for map, filter and reduce methods?
457What is the difference between map and forEach functions?
458Give an example of statements affected by automatic semicolon insertion?
459What are the event phases of a browser?
460What are the real world use cases of proxy?
461What are hidden classes?
462What is inline caching?
463What are the different ways to execute external scripts?
464What is Lexical Scope?
465How to detect system dark mode in javascript?
466What is the purpose of requestAnimationFrame method?
467What is the difference between substring and substr methods?
468How to find the number of parameters expected by a function?
469What is globalThis, and what is the importance of it?
470What are the array mutation methods?