Detailed explanation of built-in objects in js

There are 17 objects built into JS. The commonly used ones are Array objects, Date objects, regular expression objects, string objects, and Global objects. This article mainly shares with you the detailed explanation of the built-in objects of JS. I hope it can help you. .

Commonly used methods in Array objects:

Concat(): Indicates merging several arrays into one array.
Join(): Returns a string value that contains all the elements of the array joined together, with the elements separated by the specified delimiter.
Pop(): Remove the last element of the array.
Shift(): Remove the first element in the array.
Slice(start, end): Returns a segment in the array.
Push(): Add a new element to the array and return the latest length.
Sort(): Sort the array.
Reverse(): Reverse the sorting of the array.
toLocaleString(); Returns the current system time
There is only one commonly used Array object attribute:
Length: Indicates getting the current array length

Global Object
is an inherent object, the purpose is to concentrate all global methods in one in the object.
Global has no syntax and calls its methods directly.
escape(): Encodes String objects so that they are readable on all computers.
escape(charString)
Required The option charstring argument is any String object or literal to be encoded.
isNaN(): Determine whether a value is NaN.
parseInt(): Returns an integer obtained from a string

Regular expression object
This object contains a regular expression pattern and flags indicating how to apply the pattern.
Grammar 1
re = /pattern/[flags]

Grammar 2
re = new RegExp("pattern",["flags"])
re is the variable name to which the regular expression pattern will be assigned
pattern is the regular expression
flags are tags: there are three of the following
1: g (full text search)
2: i (ignore case)
3: m (multi-line search)
Use syntax 1 when the search string is known in advance. Use syntax 2 when the search string changes frequently or is unknown, such as a string entered by the user.

String Object

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。

##Math Object

ceil(): Round up.

floor(): Round down.

round(): Rounding.

random(): Take a random number.

Date object

get/setDate(): Return or set the date.

get/setFullYear(): Returns or sets the year, represented by four digits.

get/setYear(): Return or set the year.

get/setMonth(): Return or set the month. 0 is January

get/setHours(): Returns or sets hours, 24-hour format

get/setMinutes(): Returns or Set the number of minutes.

get/setSeconds(): Return or set the number of seconds.

get/setTime(): Return or set time (in milliseconds)

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