2. Lexical structure

Question 1

What is a lexical structure?

Answer 1

A set of rules that specifies how you write programs in that language

Question 2

JavaScrip is a case sensitive language

Answer 2

Yes

Question 3

A JS identifier must begin with what?

Answer 3

A letter,
an underscore,
a dollarsign

Question 4

How do you write comments in JS?

Answer 4

// this is a comment

/* this is a multi
line
comment
*/

Question 5

What is a literal?

Answer 5

A data value that appears directly in a program.

12 // The number twelve
1.2 // The number one point two
“hello world” // A string of text
‘Hi’ // Another string
true // A Boolean value
false // The other Boolean value
null // Absence of an object

Question 6

What does ASCII mean?

Answer 6

American Standard Code for Information Interchange

Question 7

Why do you use semicolons?

Answer 7

To mark an end of a statement.

Question 8

How does JS interpret this code:
let a
a
=
3
console.log(a)

Answer 8

let a; a = 3; console.log(a);

JavaScript does not treat the second line break as a semicolon because it can continue parsing the longer statement a = 3;.

Question 9

How does JS interpret this code:
let y = x + f
(a+b).toString()

Answer 9

let y = x + f (a+b).toString()
The parentheses on the second line of code can be interpreted as a function invocation of f from the first line.

For it to be a separate function, add a semicolon:
let y = x + f;