JavaScript Basics (ii)

1. Various operators

(1) Arithmetic operators

+-*/% ()

(2) Self-increment decrement operator

a++ ++a A----a

If it is added first, a plus after operation will be given

If it is a post-add, it will be given a plus after the first operation.

(3) Logical operators

&& | | Or! Non -

(4) Relational operators (comparison operators)

> <, >=, <=, = =, = =,! =,!=== (not congruent)

= = Judge content, do not care about type

= = = Care about both content and type of care

(5) Assignment operator

= right-to-left view

(6) Comma operator

，

2. Conversion of data types

(1) Forced type conversion

By using Number:number (), parseint (), parsefloat ()

String:. ToString (), String ()

Boolean:boolean ()

To convert the data to the data type of the object

(2) Implicit conversion

Number:+a; A-B; a*b,a/1,a%1 (Note: A is a string type and B is number)

String:a+ "";

boolean:!! A

All the data in JavaScript can be turned into a Boolean,

Only False,0,nan, "", undefined will turn to False when the Boolean conversion is performed,

The rest is true, including "false"

3. Process Control

(1) if

If-else

If-elseif-else

(2) switch-case-(default):

To judge a series of conditions

JavaScript Basics (ii)