JavaScript Advanced Programming Chapter fifth (1)

A reference type is a data structure that combines data and functionality, similar to a class, but with different concepts: Although ECMAScript is an object-oriented language, it does not have the basic structure of classes and structures supported by traditional object-oriented languages. Reference types are also referred to as "object definitions."

I. Type of Object

Create Instance mode:

1 using the new operator + constructor

1 var New Object (); 2 person.name = "Lillian"; 3 person.age = 29;

2 Using object literals notation

2.1 Attribute without quotation marks

1 var person = {2person     : "Lillian",3     age:294 };

2.2 Attribute Quotes

1 var person = {2     ' person ': ' Lillian ',3     ' age ': 29 , 4     5:true  // numeric attributes are automatically converted to string 5 };

2.3 Using empty curly braces

1 var person = {}; 2 person.name = "Lillian"; 3 person.age = 29;

How to access properties:

Use point or square brackets:

1 alert (person.name); 2 alert (Person[age]);

Two, array type

How to create:

1 using the array constructor

1 var New Array (); 2 var New Array (a);  // length = 3 var New Array ("Red", "blue", "yellow");  // length = 3

2 Using array literals

1 var colors = ["Red", "blue", "yellow"]; 2 var names = []; 3 var values = [1, 2,]; // don't do this, you'll create an array with 2 or 3 items 4 var options = [,,,,,]; // don't do this, you'll create an array with 5 or 6 items

In addition to the object type, the array type is probably the most common type of JavaScript, it is a lot of methods, here first through the map list, followed by examples.

To modify the contents of array arrays:

1 varcolors = ["Red", "blue", "yellow"];2Colors[0] = "green";//Modify the first item3Colors[colors.length] = "BLACK";//add an entry with a value of "black"4 5Colors.length = 5; 6Alert (colors[4]);//The length is increased by 1, but is not assigned, this is undefined7 8Colors.length = 1;9Alert (colors[1]);//Undefined, removes all items except the first item by setting the length to 1

Detects that an object is not an array:

1 if instanceof Array) {}; // not available for NetEase with multiple frames 2 if // high requirement for browser version

Conversion method:

1 varcolors = ["Red", "blue", "yellow"];2Colors.tostring ();//" Red", "blue", "yellow"3Colors.tolocalestring ();//" Red", "blue", "yellow"4Colors.valueof ();//["Red", "blue", "yellow"]5alert (colors);//" Red", "blue", "yellow"6Alert (Colors.join (","));//" Red", "blue", "yellow"7Alert (Colors.join ("| |)");//"1| | 2| | 3 "

Stack method: LIFO

1 var colors = ["Red", "blue", "yellow"]; 2 Colors.push ("Black"); 3 colors.pop (); // "BLACK"

Queue method: LILO

1 var colors = ["Red", "blue", "yellow"]; 2 Colors.push ("Black"); 3 colors.shift (); // "Red"

Reorder methods:

1     varvalues = [1,0,15,14,2];2Values.reverse ();//[2, 0, 1]3Values.sort ();//[0, 1, +, 2]4 5     functionCompare (value1, value2) {6         if(Value1 <value2) {7             return-1;8}Else if(Value1 >value2) {9             return1;Ten}Else{ One             return0; A         } -     } -  theValues.sort (Compare);//0,1,2,14,15

Operation Method:

1     //concat () Add the received parameter at the end2     varcolors = ["Red", "green", "blue"];3     varColors2 = Colors.concat ("Yellow", ["Black", "Brown"]);4     //colors2: "Red", "green", "blue", "yellow", Black "," Brown "5 6     //Slice () intercepts part of the current array7     varcolors = ["Red", "green", "blue", "yellow"];8     varColors2 = Colors.slice (1);//["Green", "blue", "yellow"]9     varColors3 = Colors.slice (1,3);//["Green", "blue"]Ten  One     //Splice () Delete and insert A     varcolors = ["Red", "green", "blue", "yellow"]; -     varremoved = Colors.splice (0,2);//starting with the first item, delete two items -      the     varcolors = ["Red", "green", "blue", "yellow"]; -     varremoved = Colors.splice (1,0, "Black");//after the second item, insert an item -  -     varcolors = ["Red", "green", "blue", "yellow"]; +     varremoved = Colors.splice ("Black");//After the second item, delete an item, and then insert an item

Location Method:

1     var numbers = [1,2,3,4,5,4,3,2,1]; 2     // 3 3     // 5 4     // 5

Iterative methods:

1 /*2 Iteration Method: function (the value of the array item, the position of the item in the array, the array object itself)3 */ 4 5 //every (): If each item returns TRUE, the function returns True6 varnumbers = [1,2,3,4,5,4,3,2,1];7 varresult = Numbers.every (function(item, index, array) {8     return(Item > 2);9 }); Tenalert (result);//false One  A //Some (): If there is an item that returns TRUE, the function returns True - varnumbers = [1,2,3,4,5,4,3,2,1]; - varresult = Numbers.some (function(item, index, array) { the     return(Item > 2); - });  -alert (result);//true -  + //Filter (): Filters out values that meet the criteria - varnumbers = [1,2,3,4,5,4,3,2,1]; + varresult = Numbers.filter (function(item, index, array) { A     return(Item > 2); at });  -alert (result);//[3,4,5,4,3] -  - //map (): Returns the result of a function call and makes up an array - varnumbers = [1,2,3,4,5,4,3,2,1]; - varresult = Numbers.map (function(item, index, array) { in     return(Item * 2); - });  toalert (result);//[2,3,6,8,10,8,6,4,2]; +  - //ForEach (): No return value the varnumbers = [1,2,3,4,5,4,3,2,1]; *Numbers.foreach (function(item, index, array) { $ alert (item);Panax Notoginseng});

To reduce the method:

1 /*2 Iteration Functions: (previous value, current value, index of item, array object)3 iterate over all items and return a final result4 Reduceright is a forward traversal from the last item in the array5 */6 varvalues = [1,2,3,4,5];7 varsum = Values.reduce (function(prev, cur, index, array) {8 //var sum = values.reduceright (function (prev, cur, index, array) {9     returnPrev +cur;Ten }); Onealert (sum);// the

JavaScript Advanced Programming Chapter fifth (1)