JavaScript Random Sorting

08.11

# JavaScript Basics
# # programming language
* Machine language
* Assembly language
* Advanced Language
* Compiled type
* Explanatory type

# # # JavaScript Development
* ECMA3 has established a position
* ECMA5
* ECMA6 (ECMA2015 ECMA2016 ECMA2017)


# # #客户端 JavaScript composition
* ECMASCRIPT (core basic grammar)
* BOM (Browser model)
* DOM (Document Object model)

# # #客户端 JavaScript composition
* ECMASCRIPT (core basic grammar)
* BOM (Browser model)
* DOM (Document Object model)



# JavaScript Basic Syntax
The use of # # # in HTML
* Use script tag to introduce JS file
* Write the JS code in the script tag

# # # JavaScript annotations
* Single-line comment//comment
* Multi-line Comment/* Comment */

# # # JavaScript directive Terminator
* Line break
* Semicolon


Output of # # # JavaScript
* Console output Console.log ()
* Bounce Box Output alert ()
* Output to page document.write ()

# JavaScript variables
### Direct amount
## #变量: Container for data loading
### variable naming convention
*   cannot start with a number
*   has numbers, letters, underscores
*   cannot make reserved words
## #命名方式
*   Small hump    userage
*   Big hump    userage
*   Hungary    user_age
### declaration variable
        &NBSP
         var variable name = value;
        var var01=val,var02=value;   //declaring multiple variables

# JavaScript data types
# # Original Type
* Number Numbers
* String Strings
* Boolean Boolean
* NULL Empty
* Undefined Not defined


# # Object Type
* Date
* Array
* Object
* .....


# # # Detection function
* typeof ()



# type
# # # Categories
* Integer integers
* Floating-point decimals

# # # Direct Volume representation
* Decimal integer or decimal 19.9
* Octal means 010
* Hexadecimal indicates 0x65
* Scientific Counting Method 7e6

# # # Special number
* InFinity Positive Infinity
*-infinity Negative infinity

### non-numeric value Nan (not a number)
*  evaluates to any number Nan
*  is not equal to any value


### numeric function
* isnan ()    determine if Nan   true/false
* isfinite ()    infinite



# string string
### definition string
*  double quotation mark
*  single quote

### escape character
\ "
\ '
\n    line break
\r     carriage return
\t     tab TAB
\v    vertical tab
\f     page Break
\b     backspace
\\ 

### string connector
*  +

 

08.14

# Data type conversions
# # # Automatic conversion (in some computing environment)
* Number Environment
* String Environment
* Boolean Environment

# # # Forced type conversions
* Number ()
* String: Pure numeric characters and null characters are converted to normal numbers, other Nan
* Boolean value: Ture:1 false:0
* String ()

* Boolean ()
* Converted to false: number 0, empty string, null and undefined
* Convert to True: value indicates something
* parseint ()
* Convert to Integer
* Differs from number: A string that begins with a digit and does not convert to Nan
* Parsefloat ()
* Convert to Decimal or integer
* Differs from number: A string that begins with a digit and does not convert to Nan



# JS Operation HTML
# # Events
* onclick

# # function
* Declaring functions

Function name () {
Code
}
* Call function

Function name ()


# # # Get elements
* document.getElementById ("")
* JS code is written behind the HTML element

# # # JS Operations HTML element properties and CSS Data
* Element object. Property name
* Element object. style. Property name
* CSS attribute name with small hump naming method. Only CSS properties that are written in the element style can be retrieved
* innerHTML Property Gets or sets the contents of the double tag



# An expression
* Simple expressions; variables, direct quantities
* Complex expression; The combination of an operator and a simple expression
* Function-Call expression



# operator
# # Arithmetic Operators
* Plus operator +
* Minus operator-
* Multiplication Sign operator *
* Division sign operator/
* Take the remainder operator (modulo)%
* Negative operator-
* Positive operator +
* Increment operator + +
* Decrement Operator--


# # comparison operator
* Equality operator = =
* Inequality operator! =
* congruent operator = = =
* Non-congruent operation operator!==
* Less than operator <
* Less than equals operator <=
* Greater than operator >
* Greater than equals operator >=
* In operator

# # logical operators
* Logic and (and) &&
* Logic or (or) | |
* Logical Non!

# # # Bitwise operators
* Bitwise AND &
* Bitwise OR |
* Bitwise NON ~
*  bitwise XOR or    ^
*  left shift     <<
*  move right    >>


### assignment operator
* =
*   +=
*  -=
*  *=
Span style= "COLOR: #808080" >*  /=
*  %=


### other operators
*  string connector +
* , operator
* typeof operator
*  comparison operator     an expression? Expression 1: expression 2
 

# operator precedence

JavaScript is organized randomly