"JavaScript advanced Programming" reading notes (i) ECMAScript basic _javascript skills

2.1 Grammar
Case sensitive, variable weak type, end-of-line semicolon optional, comment double slash, bracket indicates code block

2.2 Variables
Variables are declared with VAR, the variable's naming rule: the first character must be a letter, an underscore, or a dollar sign; the remaining characters can be underscores, dollar signs, or any letter or numeric character.

Variable Naming conventions:

Camel notation: The first letter is lowercase, and the next word begins with an uppercase letter. For example: Var mytestvalue=0,mysecondtestvalue= "HI";

Pascal notation: Capitalize the first letter, and the next words begin with an uppercase letter. For example: Var mytestvalue=0,mysecondtestvalue= "HI";

Hungarian type notation: appends a lowercase letter (or lowercase alphabetical sequence) to a variable named after the Pascal notation, indicating the type of the variable. For example, I represents an integer and S represents a string, as shown here:

var imytestvalue=0,smysecondtestvalue= "HI";

The prefix used to define ECMAScript variables using Hungarian type notation is as follows:

Type: Array prefix: a example: avalues

Type: Boolean prefix: b Example: Bfound

Type: floating-point prefix: f Example: Fvalue

Type: Function prefix: fn Example: Fnmethod

Type: integer prefix: i example: ivalue

Type: Object prefix: o Example: Otype

Type: Regular prefix: re example: Repatten

Type: String prefix: s example: svalue

Type: Variable prefix: v Example: vvalue

2.3 Key Words
The keywords defined by ECMA-262 are:

Break case Catch Continue default Delete does else finally for function if in instanceof new return switch This throw try typeof var void while with

2.4 Reserved words
The reserved words in the 3rd edition of ECMA-262 are:

Abstract Boolean byte char class const debugger Double enum export extends final float Goto implements Impo RT int interface Long native package private protected public short static super synchronized throws NT volatile

2.5 Original value and reference value
The original value (primitive value) is a simple data segment stored in the stack (stack), that is, their values are stored directly in the location where the variable is accessed.

A reference value (reference value) is an object stored in a heap (heap), meaning that the value stored at the variable is a pointer (point) that points to the memory where the object is stored.

Author: Tian Xing Jian, self-improvement