JS built-in objects
String object: A String object that provides properties and methods for manipulating a string.
Array object: A property and method for array manipulation.
Date object: A DateTime object that can obtain the system's datetime information.
Boolean object: A Boolean object, a Boolean variable that is a Boolean object. (No properties and methods are available)
Number object: Numeric object. A numeric variable is a numeric object.
Math object: A Mathematical object that provides properties and methods for mathematical operations.
Properties and methods for string objects
Length: Gets the lengths of the strings. Example: var len = strobj.length
toLowerCase (): Turns the letters in the string to lowercase. such as: Strobj.tolowercase ()
toUpperCase (): Converts the letters in a string to uppercase. such as: Strobj.touppercase ()
CharAt (Index)
Function: Returns a character that specifies the position of the subscript. If it is not found, an empty string is returned.
Syntax: Strobj.charat (Index)
Parameter: Index is the specified index number that returns a character based on the index number.
IndexOf ()
Function: Returns the index value of a substring in the original string (the lookup order is looked up from left to right). If not found, returns-1.
Syntax: Strobj.indexof (SUBSTR)
Parameter: substr represents a substring to find.
LastIndexOf ()
Function: Finds a substring in the original string, from right to left . If not found, return-1.
Syntax: Strobj.lastindexof (SUBSTR)
Parameters: Substr represents the substring to find.
SUBSTR ()
Function: Returns a substring in the original string.
Syntax: Strobj.substr (startIndex [, length])
Description: Returns the length of a character from subscript startindex.
Parameters:
startindex indicates the starting index number of the lookup;
Length is optional and returns several characters. If omitted, always returns to the end.
SUBSTRING ()
Function: Returns a substring in the original string.
Syntax: strobj.substring (StartIndex [, EndIndex])
Description: Returns all characters from the startindex start index value to the Endindex end index value.
Parameters:
StartIndex: Represents the starting index value.
EndIndex: Optional, which represents the end index value. If omitted, all characters are generally returned to the end.
Tip: If you omit the second argument, the substr () and substring () results are the same.
Note: substring () The returned characters contain startindex the character at the Endindex, not including the character at the same place.
Example:
"ABCDEFGH". substring (0,5) = "ABCDE"
"Abcdefgh". substr (0,5) = "ABCDE"
"ABCDEFGH". substring (2,3) = "C"
"Abcdefgh". substr (2,3) = "CDE"
Split () : Converts a string to an array
Function: Cuts a string into several segments. returns an array .
Syntax: Strobj.split (partition number)
Parameter: The argument is a string of a split number. Divides the string into segments with the specified partition number.
Example: "A,b,c,d". Split (",") = arr["A", "B", "C", "D"]
JS built-in object string object