JavaScript Question Answers - 181-200

181. Define unescape() and escape() functions

escape() encodes a string so it can be transmitted safely (deprecated).
unescape() decodes an encoded string (deprecated).

182. What is the difference between .call() and .apply()

- call(): Invokes a function with a given this value and arguments provided individually.
- apply(): Invokes a function with a given this value and arguments provided as an array.

183. How can you convert the string of any base to integer in JavaScript

Use parseInt(string, base). Example: parseInt("1010", 2) → 10.

184. What are the different types of errors in JavaScript

- Load-time errors
- Run-time errors
- Logical errors

185. Explain how to read and write a file using JavaScript

- In browsers: Use File API for reading, and downloads or server APIs for writing.
- In Node.js: Use fs.readFile() and fs.writeFile().

186. What are the two basic groups of datatypes in JavaScript

- Primitive types (Number, String, Boolean, Null, Undefined, Symbol, BigInt)
- Reference types (Objects, Arrays, Functions)

187. Explain the unshift() method

arr.unshift(element1, ...) adds elements to the beginning of an array and returns the new length.

188. Which statement throws (generates) an error

throw new Error("message");

189. Which method converts the date portion of a Date object into a readable string

date.toDateString()

190. Which method converts a number into an exponential notation

num.toExponential(fractionDigits)

191. Which method formats a number with x numbers of digits after the decimal point

num.toFixed(x)

192. Which method returns the date as a string, using the ISO standard

date.toISOString()

193. Which method returns the date as a string, formatted as a JSON date

date.toJSON()

194. Which method returns the date portion of a Date object as a string, using locale conventions

date.toLocaleDateString()

195. Which method converts a string to lowercase letters, according to the host's locale

str.toLocaleLowerCase()

196. Which method converts a Date object to a string, using locale conventions

date.toLocaleString()

197. Which method returns the time portion of a Date object as a string, using locale conventions

date.toLocaleTimeString()

198. Which method converts a string to uppercase letters, according to the host's locale

str.toLocaleUpperCase()

199. Which method converts a string to lowercase letters

str.toLowerCase()

200. Which method returns the topmost browser window

window.top