Summary of common techniques used to intercept and separate strings in JS, and to intercept and separate strings in js

Summary of common techniques used to intercept and separate strings in JS, and to intercept and separate strings in js

This document describes common methods for intercepting and splitting strings in JavaScript. We will share this with you for your reference. The details are as follows:

You can use substring () or slice () to intercept strings in JS ()
 
Function: substring ()

Definition: substring (start, end) indicates the string from start to end, including the start position but not the end position.

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

Example:

Var src = "images/off_1.png"; alert (src. substring (); // the pop-up value is: off.

Function: substr ()

Definition: substr (start, length) indicates to extract the length string from the start position.

Function: String Truncation

Example:

Var src = "images/off_1.png"; alert (src. substr (); // the pop-up value is: off.

Function: split ()

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

Example:

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:

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: indexOf ()

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

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

Function: lastIndexOf ()

Definition: lastIndexOf () method returns the index value of the first character of a character or string that appears from the right to the left (opposite to indexOf)

Function: returns the string index value.

Example:

Var src = "images/off_1.png"; alert (src. lastIndexOf ('/'); alert (src. lastIndexOf ('G'); // the pop-up values are: 6, 15

Supplement: differences between substr and substring Methods

Substr Method

Returns a substring of the specified length starting from the specified position.

Stringvar. substr (start [, length])

Parameters

Stringvar

Required. The String text or String object to extract the substring.

Start

Required. The starting position of the required substring. The index of the first character in the string is 0.

Length

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 stringvar.

Example

The following example demonstrates the substr method usage.

Function SubstrDemo () {var s, ss; // declare the variable. Var s = "The rain in Spain falls mainly in the plain."; ss = s. substr (12, 5); // obtain The substring. Return (ss); // return "Spain ".}

Substring Method

Returns the substring at the specified position in the String object.

StrVariable. substring (start, end)
"String Literal". substring (start, end)

Parameters

Start

Specifies the starting position of the substring. The index starts from 0.

End

Specifies the end position of the substring. The index starts from 0.

Description

The substring method returns a string that contains a substring from start to the end (excluding end.

The substring method uses a small value in start and end as the starting point of the substring. For example, strvar. substring (0, 3) and strvar. substring (3, 0) return the same substring.

If start or end is NaN or negative, replace it with 0.

The length of the substring is equal to the absolute value of the difference between start and end. For example, the length of the substring returned in strvar. substring (0, 3) and strvar. substring (3, 0) is 3.

Example

The following example demonstrates the usage of the substring method.

Function SubstringDemo () {var ss; // declare the variable. Var s = "The rain in Spain falls mainly in the plain .."; ss = s. substring (12, 17); // obtain The substring. Return (ss); // return the substring .}

I hope this article will help you design JavaScript programs.