"JavaScript advanced programming" Reading Notes (1) ECMAScript basics _ javascript tips-js tutorial

ECMAScript basics, mainly including syntax, variables, keywords, reserved words, original values and reference values, etc. 2.1 syntax
Case-sensitive, weak variable type, line-and-tail semicolons are optional, comments are diagonal lines, and parentheses indicate code blocks.

2.2 Variables
Variables are declared using var. Naming rules for variables: the first character must be a letter, underline, or dollar sign; the remaining characters can be an underscore, dollar sign, or any letter or digit.

Variable naming rules:

Camel markup: the first letter is lowercase, and the subsequent words start with an uppercase letter. For example, var myTestValue = 0, mySecondTestValue = "hi ";

Pascal markup: the first letter is capitalized, and the subsequent words start with an uppercase letter. For example, var MyTestValue = 0, MySecondTestValue = "hi ";

Hungary type labeling: append a lower-case letter (or lower-case letter sequence) to a variable named by Pascal, indicating the type of the variable. For example, I represents an integer, and s represents a string, as shown below:

Var iMyTestValue = 0, sMySecondTestValue = "hi ";

The prefix used to define ECMAScript variables using the Hungary type markup method 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 keywords
The ECMA-262 defines the Keyword:

Break case catch continue default delete do else finally for function if in instanceof new return switch this throw try typeof var void while

2.4 Reserved Words
Reserved Words in ECMA-262 3rd edition:

Abstract boolean byte char class const debugger double enum export extends final float goto implements import int interface long native package private protected public short static super synchronized throws transient volatile

2.5 Original Value and reference value
The original value is a simple data segment stored in the stack, that is, their values are directly stored in the access location of the variable.

Reference value is an object stored in heap. That is, the value stored in a variable is a pointer to the memory of the object.

Author: tianxingjian, self-improvement