JavaScript strings (String) object

1.JavaScript Strings (String) object

A String object is used to handle an existing block of characters.

1.1 JavaScript string

A string is used to store a series of characters like "John Doe".

A string can use either single or double quotation marks:

var carname="Volvo XC60"; var carname='Volvo XC60';

You use the location (index) to access any character in the string:

var character=carname[7];

The index of the string starts at zero, so the first character of the string is [0], the second character is [1], and so on.

You can use quotation marks in a string, as in the following example:

var answer="It ' s alright"; var answer="He is called ' Johnny '"; var answer='He is called ' Johnny';

Or you can use the escape character (\) in the string to quote:

var answer='it\ ' s alright'; var answer="He is called \" johnny\"";

1.2 Strings (String)

String (string) to calculate the length of the string using length property:

var txt="Hello world! " ;d Ocument.write (txt.length); var txt="abcdefghijklmnopqrstuvwxyz";d ocument.write (txt.length);

1.3 Finding a string in a string

The string uses indexOf () to position the first occurrence of a specified character in a string:

var str="Hello World, Welcome to the universe. " " ; var n=str.indexof ("welcome");

If the corresponding character function is not found, return-1

The LastIndexOf () method starts at the end of the string to find where the string appears.

1.4 Content Matching

The match () function is used to find a specific character in a string and, if found, returns the character.

var str="Hello world! " ;d ocument.write (Str.match ("World"<br>" );d Ocument.write (Str.match ("World"<br>  ");d ocument.write (Str.match ("world! "));

1.5 Replacing content

The Replace () method replaces some character with some characters in a string.

str="pleasevisit microsoft! " var n=str.replace ("Microsoft","runoob");

1.6 String Case Conversion

The string case conversion uses the function touppercase () / toLowerCase ():

var txt="Hello world! ";       // String var txt1=txt.touppercase ();   // txt1 text is converted to uppercase var txt2=txt.tolowercase ();   // txt2 text is converted to lowercase

1.7 String to Array

The string is converted to an array using the split () function:

txt="a,b,c,d,e"   //  Stringtxt.split ("," );   // use commas to separate txt.split ("");   // use spaces to separate txt.split ("| ");   //

1.8 Special Characters

In Javascript, you can use backslashes (\) to insert special symbols, such as apostrophes, quotation marks, and other special symbols.

Look at the following JavaScript code:

var txt="Vikings" from the North . " ;d ocument.write (TXT);

In JavaScript, the start and stop of a string use single or double quotation marks. This means that the above string will be cut into: We are the so-called

To resolve the above problems, you can use backslashes to escape quotation marks:

var txt="We is the so-called \" Vikings\ " from the north. " ;d ocument.write (TXT);

JavaScript will output the correct text string: We are the "Vikings" from the so-called.

The following table lists other special characters that you can use to escape special characters by using backslashes:

Code	Output
\‘	Single quotation marks
\"	Double quotes
\\	Diagonal Bar
\ n	Line break
\ r	Enter
\ t	tab
\b	Space
\f	Page change

1.9 String properties and methods

Property:

• Length
• Prototype
• Constructor
Method:
• CharAt ()
• charCodeAt ()
• Concat ()
• fromCharCode ()
• IndexOf ()
• LastIndexOf ()
• Match ()
• Replace ()
• Search ()
• Slice ()
• Split ()
• SUBSTR ()
• SUBSTRING ()
• toLowerCase ()
• toUpperCase ()
• ValueOf ()

JavaScript strings (String) object