Case Sensitivity
JavaScript is case sensitive so all the identifiers must be typed with same consistent capitalization. For example, hourNow means something different to HourNow or HOURNOW.

Whitespace is usually insignificant in JavaScript, but it is occasionally necessary to use whitespace to separate sequences of characters that would otherwise be combined into a single token. For example, in:


the space between var and greeting cannot be removed, but the other spaces can be removed.

A script is a series of instructions that a computer can follow one-by-one. Each individual instruction or step is known as a statement. Statements should end with a semicolon. A statement is an individual instruction that the computer should follow.


1. Single-Line Comments
In a single-line comment, anything that follows the two forward slash characters // on that line will not be processed by the JavaScript interpreter.

2. Multi-Line Comments
To write a comment that stretches over more than one line, you use a multi-line comment, starting with the /* characters and ending with the * / characters. Anything between these characters is not processed by the JavaScript interpreter.