Common Methods for JS string truncation and examples _ javascript skills

There are many ways to intercept strings. You can select a string based on your actual needs during use. The following describes some common methods and examples. Use substring () or slice ()

Function: split ()
Function: uses a specified separator to split a string and store it in an array.
Example:

The Code is as follows:

Str = "jpg | bmp | gif | ico | png ";
Arr = theString. split ("| ");
// Arr is an array containing character values "jpg", "bmp", "gif", "ico", and "png"

Function: John ()
Function: combines an array into a string using the separator you selected.
Example:

The Code is as follows:

Var delimitedString = myArray. join (delimiter );
Var myList = new Array ("jpg", "bmp", "gif", "ico", "png ");
Var portableList = myList. join ("| ");
// The result is jpg | bmp | gif | ico | png.

Function: substring ()
Function: String truncation. For example, substring () is used to obtain "Minidx" from "MinidxSearchEngine)

Function: indexOf ()
Function: returns the subscript of the first character matching the substring in a string.

The Code is as follows:

Var myString = "JavaScript ";
Var w = myString. indexOf ("v"); w will be 2
Var x = myString. indexOf ("S"); x will be 4
Var y = myString. indexOf ("Script"); y will also be 4
Var z = myString. indexOf ("key"); z will be-1

Continued:

1. substring Method

Definition and usage
The substring method is used to extract characters of a string between two specified subscripts.

Syntax
StringObject. substring (start, stop)

Parameter description
Start is required. A non-negative integer that specifies the position of the first character of the substring to be extracted in the stringObject.
Optional. A non-negative integer is 1 more than the position of the last character of the substring to be extracted in the stringObject. If this parameter is omitted, the returned substring ends at the end of the string.

Return Value
A new string. The value of this string contains a substring of stringObject. Its content is all characters from start to stop-1, and its length is stop minus start.

Description
The substring returned by the substring method includes the start character, but not the end character.
If start and end are equal, this method returns an empty string (a string with a length of 0 ).
If start is greater than end, this method swaps the two parameters before extracting the substring.
If start or end is negative, it is replaced with 0.

2. substr Method

Definition and usage
The substr method returns a substring of the specified length starting from the specified position.

Syntax
StringObject. substr (start [, length])

Parameter description
Start is required. The starting position of the required substring. The index of the first character in the string is 0.
Length is optional. The number of characters to be included in the returned substring.

Description
If the length is 0 or negative, an empty string is returned.
If this parameter is not specified, the substring will continue to the end of the stringObject.

Example:

The Code is as follows:

Var str = "0123456789 ";

Alert (str. substring (0); ------------ "0123456789"
Alert (str. substring (5); ------------ "56789"
Alert (str. substring (10 ));-----------""
Alert (str. substring (12 ));-----------""
Alert (str. substring (-5); ----------- "0123456789"
Alert (str. substring (-10); ---------- "0123456789"
Alert (str. substring (-12); ---------- "0123456789"
Alert (str. substring (0, 5); ---------- "01234"
Alert (str. substring (0, 10); --------- "0123456789"
Alert (str. substring (0, 12); --------- "0123456789"
Alert (str. substring (2, 0); ---------- "01"
Alert (str. substring (2, 2 ));----------""
Alert (str. substring (2, 5); ---------- "234"
Alert (str. substring (2, 12); --------- "23456789"
Alert (str. substring (2,-2); --------- "01"
Alert (str. substring (-01234"
Alert (str. substring (-1,-5 ));--------""

Alert (str. substr (0); --------------- "0123456789"
Alert (str. substr (5); --------------- "56789"
Alert (str. substr (10 ));--------------""
Alert (str. substr (12 ));--------------""
Alert (str. substr (-5); -------------- "0123456789"
Alert (str. substr (-10); ------------- "0123456789"
Alert (str. substr (-12); ------------- "0123456789"
Alert (str. substr (01234"
Alert (str. substr (0, 10); ------------ "0123456789"
Alert (str. substr (0, 12); ------------ "0123456789"
Alert (str. substr (2, 0 ));-------------""
Alert (str. substr (2, 2); ------------- "23"
Alert (str. substr (2,5); ------------- "23456"
Alert (str. substr (2,12); ------------ "23456789"
Alert (str. substr (2,-2 ));------------""
Alert (str. substr (-1, 5); ------------ "01234"
Alert (str. substr (-1,-5 ));-----------""