javascript-Basic Grammar (4)

Global method, and Number object

Show global methods and number for the global

  Alert (parseint ("123" + 1));         Outln (parseint ("abc"));//nan, illegal         var val = parseint ("abc");         Outln ("value =" +isnan (val)),//isnan to determine whether the illegal         var val2 = parseint ("123AFSA");//val2 = 123         outln (VAL2);//Note that If the argument starts with a number, the Parseint method retains the previous valid number, followed by discard         //And the number is not converted, so the regular expression is used to determine whether the elements are valid numbers          //Specify the binary format to decimal         var val3 = parseint ("123", "ten"),//123         var val4 = parseint ("2",//6,            //decimal to other binary, need to use Number object         var num = new Number (6);         Outln (num.tostring (2));//110, specify 6 as binary            var num1 = 60;//There is no new number         outln (num1.tostring);//3c         Note there may be a question here, that is, NUM1 is a numeric value, and how the value can be used with the ToString () method         //js is an object-based, regardless of the write divine Code) variables, functions, etc.) at the bottom are objects,         //So when using number, seldom use the new Number, which is similar to automatic boxing in Java

JS's unique statement for in statement:

format, for (variable in object)//statement that iterates over an object
For (i in arr) {
Document.writeln (i);
}

JS Custom Object

Because JS is based on the object, so he does not have the ability to describe things, but in JS can use the function to simulate the object-oriented description

First: Add more properties and behaviors to the object

function person () {//equals constructor           //alert ("person constructor Run");        }         By describing the creation of the object, new         var p = new person ();         JS in the object to add attributes, with the P. Property name can be        p.name = "a";        P.age = 1;        P.show = function () {//define P-Object Functions            alert ("Show is Running" +this.name+this.age);        }        P.show ();

The second type: for encapsulation, more in describing things

function Person (name,age) {            this.name = name;            This.age = age;            This.setname = function (name) {                this.name = name;            }            This.getname = function () {                return this.name;            }        }         var p = new Person ("a", 1);         Alert (P.getname ());

Third: Use {} to define the property and value of the key-value pair way

var P = {name: "haha", "age": 100,//key-value pair, the value must be a colon, the key can be not "getName": function () {//key-value pair and key-value pairs are separated by commas            return this.name;            },getage:function () {return this.age; }}//Alert (P.getage ());//note detection is not strict, written in lowercase P, also do not error//Object Call member There are two ways, object. Property name Object [property name] Alert (        p["name"]);          Alert (p["name"]+p["Getage"] ());//Note The calling method is followed by ()/* function person (name,age) {this.name = name;          This.age = age;          This.setname = function (name) {this.name = name;          } this.getname = function () {return this.name;      }} var p = new Person ("a", 1);      For (I in P) {Document.writeln (p[i]); } */var map = {3: "You", 5: "I", 4: "It"}/*for (i in map) {Document.writeln (map         [i]); } outln (map["5"]);//Note If it is a number, do not add "*/var GetKey = function (key) {return map[Key];         } var mm = GetKey (5); alert (mm);

Some naming formats for JS

Define an object variable, Oxx
type int variable IXX
Boolean type BXX
Type string variable SXX

Some complex definition formats

  var mm = {          //name:["SDF", "SD", "DFG", "CD"],age:[13,11,12,13]           names:[{name: "A"},{name: "B"},{name: "C"}]       }         //alert (mm.name[2]);         alert (mm.names[1].name);         for (var i = 0;i<mm.names.length;i++) {             alert (mm.names[i].name);         }

javascript-Basic Grammar (4)