Home Web Front-end JS Tutorial Detailed explanation of js basic built-in objects

Detailed explanation of js basic built-in objects

Dec 13, 2017 pm 02:50 PM
javascript object Detailed explanation

Almost everything in js can be called an object, including values, strings, dates, arrays, functions, etc. In this article, we mainly share with you the basic knowledge of js built-in objects, hoping to help everyone.
The following is a summary of some built-in objects:

1. To declare an object, you can use the new keyword
such as:

1

2

var mydate =new Date(); 

//这里使用了内置对象 Date();

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2. To access an object, use the following form:

1

objectName.methodName();

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3. Access object properties:

1

objectName.propertyName;// var arr=new Array(3);  声明对象// alert( arr.length);    访问对象的length属性

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Copy after login

1. Date object (Date())

Define a date object

1

var mydate=new Date();

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Copy after login

Date( ) objects commonly used methods for processing dates and times are:

1

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get/setDate():返回或设置日期。

 

get/setFullYear():返回或设置年份,用四位数表示。

 

get/setYear():返回或设置年份。

 

get/setMonth():返回或设置月份。0为一月

 

get/setHours():返回或设置小时,24小时制

 

get/setMinutes():返回或设置分钟数。

 

get/setSeconds():返回或设置秒钟数。

 

get/setTime():返回或设置时间(毫秒为单位)

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Copy after login

2. Array object (Array())

Define an array object

1

var myarray =new Array();

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Copy after login

Array() object is commonly used The methods are:

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Concat():表示把几个数组合并成一个数组。

Join():返回字符串值,其中包含了连接到一起的数组的所有元素,元素由指定的分隔符分隔开来。

Pop():移除数组最后一个元素。

Shift():移除数组中第一个元素。

Slice(start,end):返回数组中的一段。

Push():往数组中新添加一个元素,返回最新长度。

Sort():对数组进行排序。

Reverse():反转数组的排序。

toLocaleString();返回当前系统时间

Array对象属性常用的只有一个:

Length:表示取得当前数组长度

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Copy after login

3. String (String())
Define string object:

1

var mystring="hello"//string 类型var mystring1=new String("hello");   //object类型

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Copy after login

Commonly used methods of string object:

1

2

3

4

5

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7

8

9

10

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13

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15

charAt():返回指定索引的位置的字符

concat():返回字符串值,表示两个或多个字符串的连接

match():使用正则表达式模式对字符串执行查找,并将包含查找结果最为结果返回

function MatchDemo(){

   var r, re;         // 声明变量。

   var s = "The rain in Spain falls mainly in the plain";

   re = /ain/i;    // 创建正则表达式模式。

   r = s.match(re);   // 尝试匹配搜索字符串。

   return(r);         // 返回第一次出现 "ain" 的地方。 }

 

Replace(a,b):字符b替换a Search(stringObject):指明是否存在相应的匹配。如果找到一个匹配,search 方法将返回一个整数值,指明这个匹配距离字符串开始的偏移位置。如果没有找到匹配,则返回 -1。

Slice(start,end):返回字符段片段 Split():字符串拆分

Substr(start,length):字符串截取

Substring(start,end)取得指定长度内的字符串 toUpperCase():返回一个字符串,该字符串中的所有字母都被转化为大写字母。

toLowerCase():返回一个字符串,该字符串中的所有字母都被转化为小写字母。

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Copy after login

IV , Math()

Commonly used methods of Math() objects are:

1

ceil():向上取整。floor():向下取整。round():四舍五入。random():取随机数。

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Copy after login

5. Global()

Commonly used methods of Global objects are:

1

2

3

4

5

6

Global无语法,直接调用其方法。

escape(): 对 String 对象编码以便它们能在所有计算机上可读.

escape(charString)

必选项 charstring 参数是要编码的任意 String 对象或文字。

isNaN():判断一个值是否是NaN。

parseInt():返回由字符串得到的整数

Copy after login
Copy after login

6. Regular expressions
Commonly used methods:

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exec方法:

用法:var arr=regexp.exec(string)regexp:匹配用的正则表达式string:匹配用字符串

功能:该函数通过对传入的string进行一次匹配检测,获得字符串中第一个满足正则表达式的内容,获取字符串中第一个与正则表达式匹配的内容,并且将匹配的内容和子匹配的结果存放在返回的数组中。

返回值:数组,arr[0]为传入的string,arr[1]到arr[arr.length=1]是满足正则表达式的匹配结果.

当不存在匹配的内容时,exec方法返回null。

 

test方法

用法:var res=regexp.test(string)

功能:指出被查找的字符串中是否存在满足正则表达式要求的内容

返回值:boolean   存在返回true,不存在返回falsereplace方法

用法:str=str.replace(regexp,"替换后的值")

功能:替换字符串,将满足正则表达式要求的部分替换,“替换后的值”也可以利用function动态替换,如:

str.replace(regexp,function(){return this+"***"}

返回:替换后的字符串split方法

用法:var arr=str.split(regexp)

功能:将str以一定的规则分割

返回:分割后的数组

 

search方法

用法:var index=str.search(regexp)

功能:查找第一次出现满足表达式的位置

返回:第一次出现的位置

 

match方法

用法:var arr=str.match(regexp)

功能:将字符串中能够与正则表达式匹配的部分以数组形式返回

返回:满足正则表达式的子串数组,如果正则表达式采用全局匹配,返回多个,否则只返回第一个4,常用附加参数

 

/g

全局匹配

exec,match,replace方法中:regexp不加/g,只返回第一个匹配结果。

 

/i

忽略大小写

 

/m

进行多行匹配,只有当使用^和$时才会起作用,如果不加/m,只在第一行匹配。

Copy after login
Copy after login

1

js中几乎所有的事物都可以称之为对象,包括像数值、字符串、日期、数组,函数等等。下面是一些内置对象的总结:

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1. To declare and define an object, you can use the new keyword
such as:

1

2

var mydate =new Date(); 

//这里使用了内置对象 Date();

Copy after login

2. To access an object, use the following Form:

1

objectName.methodName();

Copy after login
Copy after login

3. Access object attributes:

1

objectName.propertyName;// var arr=new Array(3);  声明对象// alert( arr.length);    访问对象的length属性

Copy after login
Copy after login

1. Date object (Date())

Define a date object

1

var mydate=new Date();

Copy after login
Copy after login

Date() objects commonly used methods for processing dates and times are:

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

get/setDate():返回或设置日期。

 

get/setFullYear():返回或设置年份,用四位数表示。

 

get/setYear():返回或设置年份。

 

get/setMonth():返回或设置月份。0为一月

 

get/setHours():返回或设置小时,24小时制

 

get/setMinutes():返回或设置分钟数。

 

get/setSeconds():返回或设置秒钟数。

 

get/setTime():返回或设置时间(毫秒为单位)

Copy after login
Copy after login

2. Array object (Array())

Define an array object

1

var myarray =new Array();

Copy after login
Copy after login

Array( ) Commonly used methods of objects are:

1

2

3

4

5

6

7

8

9

10

11

Concat():表示把几个数组合并成一个数组。

Join():返回字符串值,其中包含了连接到一起的数组的所有元素,元素由指定的分隔符分隔开来。

Pop():移除数组最后一个元素。

Shift():移除数组中第一个元素。

Slice(start,end):返回数组中的一段。

Push():往数组中新添加一个元素,返回最新长度。

Sort():对数组进行排序。

Reverse():反转数组的排序。

toLocaleString();返回当前系统时间

Array对象属性常用的只有一个:

Length:表示取得当前数组长度

Copy after login
Copy after login

3. String (String())
Define string objects:

1

var mystring="hello"//string 类型var mystring1=new String("hello");   //object类型

Copy after login
Copy after login

Commonly used methods of string objects:

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

charAt():返回指定索引的位置的字符

concat():返回字符串值,表示两个或多个字符串的连接

match():使用正则表达式模式对字符串执行查找,并将包含查找结果最为结果返回

function MatchDemo(){

   var r, re;         // 声明变量。

   var s = "The rain in Spain falls mainly in the plain";

   re = /ain/i;    // 创建正则表达式模式。

   r = s.match(re);   // 尝试匹配搜索字符串。

   return(r);         // 返回第一次出现 "ain" 的地方。 }

 

Replace(a,b):字符b替换a Search(stringObject):指明是否存在相应的匹配。如果找到一个匹配,search 方法将返回一个整数值,指明这个匹配距离字符串开始的偏移位置。如果没有找到匹配,则返回 -1。

Slice(start,end):返回字符段片段 Split():字符串拆分

Substr(start,length):字符串截取

Substring(start,end)取得指定长度内的字符串 toUpperCase():返回一个字符串,该字符串中的所有字母都被转化为大写字母。

toLowerCase():返回一个字符串,该字符串中的所有字母都被转化为小写字母。

Copy after login
Copy after login

4. Math()

The commonly used methods of Math() objects are:

1

ceil():向上取整。floor():向下取整。round():四舍五入。random():取随机数。

Copy after login
Copy after login

5. Global()

The commonly used methods of Global objects are:

1

2

3

4

5

6

Global无语法,直接调用其方法。

escape(): 对 String 对象编码以便它们能在所有计算机上可读.

escape(charString)

必选项 charstring 参数是要编码的任意 String 对象或文字。

isNaN():判断一个值是否是NaN。

parseInt():返回由字符串得到的整数

Copy after login
Copy after login

6. Regular expression
Commonly used methods:

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

exec方法:

用法:var arr=regexp.exec(string)regexp:匹配用的正则表达式string:匹配用字符串

功能:该函数通过对传入的string进行一次匹配检测,获得字符串中第一个满足正则表达式的内容,获取字符串中第一个与正则表达式匹配的内容,并且将匹配的内容和子匹配的结果存放在返回的数组中。

返回值:数组,arr[0]为传入的string,arr[1]到arr[arr.length=1]是满足正则表达式的匹配结果.

当不存在匹配的内容时,exec方法返回null。

 

test方法

用法:var res=regexp.test(string)

功能:指出被查找的字符串中是否存在满足正则表达式要求的内容

返回值:boolean   存在返回true,不存在返回falsereplace方法

用法:str=str.replace(regexp,"替换后的值")

功能:替换字符串,将满足正则表达式要求的部分替换,“替换后的值”也可以利用function动态替换,如:

str.replace(regexp,function(){return this+"***"}

返回:替换后的字符串split方法

用法:var arr=str.split(regexp)

功能:将str以一定的规则分割

返回:分割后的数组

 

search方法

用法:var index=str.search(regexp)

功能:查找第一次出现满足表达式的位置

返回:第一次出现的位置

 

match方法

用法:var arr=str.match(regexp)

功能:将字符串中能够与正则表达式匹配的部分以数组形式返回

返回:满足正则表达式的子串数组,如果正则表达式采用全局匹配,返回多个,否则只返回第一个4,常用附加参数

 

/g

全局匹配

exec,match,replace方法中:regexp不加/g,只返回第一个匹配结果。

 

/i

忽略大小写

 

/m

进行多行匹配,只有当使用^和$时才会起作用,如果不加/m,只在第一行匹配。

Copy after login
Copy after login

Related recommendations:

JavaScript built-in objects

JavaScript core reference tutorial built-in objects_js object-oriented

JavaScript study notes built-in objects_basic knowledge

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