Web Front End Learning-first lesson JavaScript

Q1: What are the data types?

5 Simple data types: undefined,null,boolean,number,string;

1 Complex data types: object.

Undefined only one value: undefined;

Null has only one value: null; (Represents an empty object pointer)

Boolean has two literal values: true,false; (case-sensitive, true and false, etc. are not Boolean, just identifiers)

Number value: Integer, floating point, decimal, octal (first bit must be 0, strict mode is not valid), Hex (first two digits must be 0x), numeric range (most browsers number.min_value:5e-324; number.max_value:1.7976931348623157e+308, you can use Isfinite (number) to determine whether the range, the super-range after the positive number automatically converted to Infinity value, negative for-infinity); NaN (not a number); Numeric conversions: Numbers ("123") ... ; parseint ("123blue"); parseint ("AF", 16), the second parameter is the number of transitions used in the conversion, parsefloat ("0xA"); Parsefloat ("3.125e7");

String type: Character literal (\b,\f,\\), string can be added, converted to string, age.tostring ();

Alert (String (value));

Object type: combination of data and function; var o = new Object (); Properties and methods: Constructor;hasownproperty (PropertyName); ispropertypeof (Object); Propertyisenumberable (Propername) (checks if the property can use the for-in statement); tolocalstring;tosting (); ValueOf ().

Q2: What are function definitions and object definitions?

function definition: 1. function declaration

function Fun () { Expression .... };

function expression

Var fun = function () { Expression .... } Var fun1 = function fun2 () { Expression ..... }//FUN1 () =fun2 () Var MyObject = new Object (); Myobject.fun = function () { Expression ..... }

function expression

Var fun = new function () { Expression ..... } Var Creatfun (parameter) { Return fun1 (parameter1,parameter2,..., expression ...); }//use: creatfun.fun1 (Parameter1,parameter2 ...)

Object definition: (http://www.w3school.com.cn/js/pro_js_object_defining.asp)

Original mode: var obj = new Object; Obj.att= ""; obj.fun = function () {};

Factory mode: Function Creatobj () { Var obj1 = new Object; Obj1.att = ""; Obj1.fun = function () {}; Return obj1; }

Constructor method: Function Creatobj () { This.att = ""; THIS.ATT1 = ""; Obj1.fun = function () {}; } Var OBJ = new Creatobj ();

Prototype mode: Function obj{ } Obj.att = ""; obj.fun1= function () {}; Var myobj1 = new OBJ ();

Constructor/prototype for

Mix: Function car (scolor,idoors,impg)  {   this.color = scolor;   this.doors = idoors;   this.mpg = impg;   this.drivers = new array ("Mike", "John"); }   Car.prototype.showcolor = function ()  {   alert ( This.color); } Var ocar1 = new car ("Red", 4,23); Var ocar2 = new car ("Blue", 3,25); OCar1.drivers.push ("Bill"); Alert (ocar1.drivers);//output   "Mike,john,bill" Alert (ocar2.drivers);//output   "Mike,john"

Dynamic Prototyping methods: function Car (scolor,idoors,impg) { This.color = Scolor; This.doors = idoors; This.mpg = Impg; This.drivers = new Array ("Mike", "John"); if (typeof car._initialized = = "undefined") { Car.prototype.showColor = function () { alert (This.color); }; Car._initialized = true; } } Var va = new Car (+/-); Va.showcolor ();

Web Front End Learning-first lesson JavaScript