JavaScript Learning notes--1. Basic knowledge

1. Using JS in HTML

<Script> Dosomething</Script><Scriptsrc= "Test.js"></Script><ahref= "Javascript:do Something">Link</a><Buttononclick= "Do Something">Button</Button>

PS: Multiple JS fragments or JS files in an HTML file are interlinked

2. Output

Alert (' Hello World ')    // box output document.write (' Hello World ')/    /  In-document output console.log (' Hello World ')    //console panel output

3. Syntax

Naming conventions:

Naming to make sense

Cannot start with a number

Cannot use System keywords, reserved words

Case:

Case sensitive

Variable name and function name using hump naming (AAABBBCCC)

Object name uppercase per first letter (object)

Use of semicolons:

var true;    // function execution statement, plus semicolon if (a) {  console.log (' Hello world! ') );  }     // struct definition statements, without semicolons

Comments:

Single-line Comment

/* * * Multi-line Comment

4. Variables

var variable name = variable value;

5. Data type

typeof ()//can be used for output variable types

Types include:

Number//digit, including integer and floating point (when processed or differentiated), because the floating-point number is approximate, do not use = = when judging

string//character; use + sign for connection, escape using \

// Example:　　var a = ' world '; Console.log (' \ ' Hello ' + A + '!\ '); // ' Hello world! '

Boolean//Boolean;

object//objects; array and null are also part of this class, but they are still distinguished when processed

function//functions;

Undefined//undefined;

6. Operators

Arithmetic operator +-*/% + +--

Assignment operator = + = = *=/=%=

Conditional operators > < = = = >= <= = = =!==

Logical Operators && | | ! ^

Bitwise operators >> >>> << | & ~

Ternary operator? :

7. Process Control

Sequential structure

Branching structure

if(BOOL) {...}//Single channel
if(BOOL) {...}Else{...}//Two-way
if(bool) {...}Else if(bool) {...}Else {  ...  } //multi-channel for range matching
Switch(var) {   Casevalue1: ... Break;  Casevalue2: ... Break; default:     ...    } //multi-path for single value matching

Loop structure

 while(BOOL)//to judge the execution first, belong to the conditional type//Example:vari = 0; while(I < 100) {Console.log (‘#‘); I++; } Do- while()//perform the re-judgment first . for()//side judgment side Execution;//Example: for(vari=1;i<=9;i++){   for(varj=1;j<=9;j++) {Console.log (J+ "*" +i+ "=" + (j*i)); } console.log ("------------------");} Break    //Exit LoopContinue    //exit this cycle

Error handling

Try {...} Catch (e) {...}    // attempt and error handling

@zhnoah
Source: http://www.cnblogs.com/zhnoah/
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JavaScript Learning notes--1. Basic knowledge