1.

　　 JS programs are programed by Unicode character.

1.1

　　JS programs are case-sensitive.

　　HTML--non-case-sensitive.

　　XHTML--case-sensitive.

　　When objects and properties in JS are same to the tags and properties in HTML, the JS must be lowercase while HTML can be itsself.

1.2

　　JS will ignore the space between tokens. At most time, JS will ignore newlines.

1.3 

　　JS contains special characters to express special symbol. Use "\n" as prefix. Just like "\nu0072".

1.4

　　Unicode had defined the first choice of code formats for every character.

2.

　　JS supports two kinds of notes:

　　"//" for a line

　　"/*----*/" for a block

3.

　　Literals: "Hello World", 12, null, ‘javascript‘

4.

　　Tokens of JS must begin with letter, _, or $.

　　Tokens of JS also support all character in Unicode.

　　JS had defined some reserved words. Them cannot be the token.

5.

　　When the sentence has exclusive line, it can end without ";".

　　This is a bad habit.

JS - Lexical Structure