js

Question 1

Closures

Answer 1

an inner function that has access to the outer (enclosing) function’s variables—scope chain

Question 2

Constructor

Answer 2

special method for creating and initializing an object created within a class

Question 3

Destructuring Object

Answer 3

JavaScript expression that makes it possible to unpack values from arrays, or properties from objects, into distinct variables.

var instructor = {
    firstName: "Elie",
    lastName: "Schoppik"
}

var {firstName:first, lastName:last} = instructor

first; // “Elie”
last

Question 4

Expressions

Answer 4

Produces value

Question 5

Declaration(statement)

Answer 5

Performs an action

Question 6

Inheritence

Answer 6

https://hackernoon.com/inheritance-in-javascript-21d2b82ffa6f

Question 7

Side Effects

Answer 7

any interaction with the outside world from within a function.
NO SIDE EFFECTS
function priceAfterTax(productPrice) {
 return (productPrice * 0.20) + productPrice;
}
SIDE EFFECTS
var tax = 20;
function calculateTax(productPrice) {
 return (productPrice * (tax/100)) + productPrice; 
}

Question 8

Rest Operator

Answer 8

used to get the arguments list passed to function on invocation and in array destructur

Question 9

Spread Operator

Answer 9

fills the function invocation arguments with values from an array

Question 10

Strict Mode

Answer 10

Deleting a variable, a function, or an argument will result in an error
No More Auto Global Variable Declaration.

Question 11

Classes

Answer 11

creates an object that is linked to a prototype. Changes to that prototype propagate to the new object, even after instantiation.

Question 12

Super

Answer 12

The super keyword is used to access and call functions on an object’s parent.

Question 13

‘new’

Answer 13

creates an instance of a user-defined object type or of one of the built-in object types that has a constructor function

Question 14

Recursiomn

Answer 14

the ability to call a function from within itself.

Question 15

Primitives

Answer 15

Boolean
Null
Undefined
Number
String
Symbol (new in ECMAScript 6)

Question 16

Object

Answer 16

collection of properties, and a property is an association between a name (or key) and a value.

Question 17

Regular expressions(regex)

Answer 17

patterns used to match character combinations in strings

Question 18

arrow functions

Answer 18

a function expression and does not have its own this, arguments, super, or new.target.

Question 19

Promise

Answer 19

Object that represents a task that will be completed in the future.

Question 20

Method

Answer 20

A JavaScriptmethodis a property containing afunction definition.

Question 21

Properties

Answer 21

The values associated with a JavaScript object.