JS Learning--Object Foundation

JavaScript is an object-oriented language. Everything in JavaScript is an object, but does not use a class, it is based on a prototype (prototype). An object is a special kind of data that has properties and methods.

creating JavaScript objects

Mode 1. Defining and creating an object instance

var person=New Object (); // Create a new instance of the object person.name= "name"; // Add the name attribute person.age=10; // Add Age Property // Another method var person={name: "Name", age:10= "Blue";   Add a new attribute to an already existing object by assigning a value

Mode 2. Using the Object Builder

Just like the constructor in C + +, the function name and the class name are identical

 //  object builder   function   person (name, age) { this .    Name = name;           this . Age = age;  //  method: Function Inside object  this . ChangeName = ChangeName;  function   ChangeName (name) { this . Name = name; }}  //  Create instance   var  myperson = new  person ("name", "ten"); 

Number Object

JavaScript has only one numeric type, all numbers are 64 bits, all floating-point types

• accuracy : integers (up to 15 digits), decimals (up to 17 bits)
• In-process

var y = 0377; 0 opening indicates 8 binary

var x = 0xff;//0x means 16 binary

var z = 10;//defaults to 10 binary

Number.tostring (16);//using the ToString () method to output the number of different binary

• Special values

Infinity: MyNumber = Infinity; Positive and negative infinity

Non-numeric value: MyNumber = NaN; IsNaN (MyNumber);//Whether it is a Nan value

String Object

Assign value	var str = "STR";//You can use double quotes var str = ' str ';//can be enclosed in single quotes
Access	var character = str[1];//use subscript to access characters in a string
Length	var lenth = Str.length;//length property to calculate string length
Find a location	var n = str.indexof ("abc");//Position ABC where it first appears in STR, not found returns 1 var str = "AABC"; var obj = Str.match ("abc");//Find the string ABC in STR and return the found result object, matching only once obj result: ["abc", INDEX:1, Input: "AABC", Length:3] [The string to find, the string to look up in str, the input string]
Replace	var n = str.replace ("A", "B");//Replace the A in STR with B, replace only the first a, and return the replaced string
Case-sensitive changes	var up = Str.touppercase ();//convert All to uppercase var low = Str.tolowercase ();//convert All to lowercase
Convert an array	var sstr = Str.split (",");//use String to divide it into groups

                Date Dates Object               & nbsp; the month represented by numbers is 1 smaller than the actual number, which is 0 = January

var date1 = new Date ();

var date2 = new Date ();

if (date1 = = date2) {}

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get	var date = new Date () ;//Current date and time var year = Date.getfullyear ();//Get years var day = Date.getday ();//Get date ...
Create	var date = new Date (); /Current date and time var date = new Date (1000),//1000 milliseconds after 1970.01.01 8 o'clock in the morning var date = new Date ("October 13, 1975 11:13:00 ");//String to get the date var date = new Date (year, month, day, hours, minutes, seconds, milliseconds); //month=2, last set to March
set	var date = new Date (); /p> Date.setfullyear (2010,0,14);//month set to 0, actually 1
comparison

                array Array object               

1. var arr=new Array ();

Arr[0] = 0;arr[1]=1;

2. var arr=new Array (0,1);

3. var arr=[0,1];

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Create array
Access array	arr[0] = 1;//use subscript to access
Array can have different objects (similar to Python)	var arr=new Array (); Arr[0] = 0; Arr[1] = "1";
Number of elements	var n = arr.length;
positioning	var n = arr.index of (0);

the Boolean object represents two values of true or false

var B = new Boolean ();//0-1 null "" False undefined Nan means false

the Math object performs common arithmetic tasks

Rounded	var d = math.round (2.4);
Random number	var d = math.random ();
Maximum/Small value	var d = Math.max (1,2,3,4); var d = math.min (1,2,3,4);
Constant	Math.PI MATH.E math.sqrt (16); square Root 16 Math.sqrt2 Radical 2 math.sqrt1_2 square root 1/2 MATH.LN2 Math.ln10 E as base MATH.LOG2E 2 for Bottom math.log10e 10

BOM Browser Object Model

Windows browser window

• Window.screen User screen information, can not be prefixed with window
• Window.location the URL of the current page without a window prefix
• Window.history browser history, without window prefix
• Window.navigator browser information, such as name, version, language, etc., can not be prefixed with window

pop-up window

Warning Box: alert ("no! error! ")

Confirmation Box: var r = comfirm ("please confirm");//Confirm =true Cancel =false

Prompt box: prompt ("input prompt", "default value");//Prompt user to enter information

Timing Events

var interval = setinterval(funname,3000);// loop execution funname function every 3000 milliseconds

Clearinterval (interval);//stop interval loop execution

var timeout = SetTimeOut(Funname, 2000)//After 2000 milliseconds, execute once funname function, do not loop

Cleartimeout (timeout);//Cancel this execution

JS Learning--Object Foundation