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COMPUTER SOFTWARE APPLICATION - CITS

JavaScript Comments
Not all JavaScript statements are “executed”.
Code after double slashes // or between /* and */ is treated as a comment.
Comments are ignored, and will not be executed:
let x = 5; // I will be executed
// x = 6; I will NOT be executed

You will learn more about comments in a later chapter.
JavaScript Identifiers / Names
Identifiers are JavaScript names.
Identifiers are used to name variables and keywords, and functions.

The rules for legal names are the same in most programming languages.
A JavaScript name must begin with:
• A letter (A-Z or a-z)
• A dollar sign ($)
• Or an underscore (_)

Subsequent characters may be letters, digits, underscores, or dollar signs.
Note
Numbers are not allowed as the first character in names.
This way JavaScript can easily distinguish identifiers from numbers.
JavaScript is Case Sensitive

All JavaScript identifiers are case sensitive.
The variables lastName and lastname, are two different variables:
let lastname, lastName;
lastName = “Doe”;
lastname = “Peterson”;
JavaScript does not interpret LET or Let as the keyword let.
JavaScript and Camel Case
Historically, programmers have used different ways of joining multiple words into one variable name:
Hyphens:
first-name, last-name, master-card, inter-city.
Hyphens are not allowed in JavaScript. They are reserved for subtractions.
Underscore:
first_name, last_name, master_card, inter_city.
Upper Camel Case (Pascal Case):
FirstName, LastName, MasterCard, InterCity.
Lower Camel Case:
JavaScript programmers tend to use camel case that starts with a lowercase letter:
firstName, lastName, masterCard, interCity.
JavaScript Character Set

JavaScript uses the Unicode character set.
Unicode covers (almost) all the characters, punctuations, and symbols in the world.

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CITS : IT&ITES - Computer Software Application - Lesson 37 - 46