String Objects in JavaScript

Vijayakumar S
2y
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Article

Introduction

In my previous article, I explained the underlying concepts and methods, and properties. In this article, we learned about String objects and String methods and Properties in JavaScript.

Definition

A String is a collection of characters (or) sequence of characters, which is always enclosed with a single (‘’) or double quote (“”). A JavaScript string stores a series of

characters like “c sharp corner”.

Uses of string

It is used to store single characters, and
It stores an array of characters
It is used to manipulate text – search a particular letter and replace text

We can see one small example:

Example

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>String</title>
</head>
<body>
    <h2>String </h2>
    <script type="text/javascript">
    var str = "vijayakumar S"; //string double quotes
    var str1 = 'C sharp corner'; // single quotes
    document.write (str+"<br>" );
    document.write (str1+"<br>" );
    </script>
</body>
</html>

Output

String Objects In JavaScript

Note

It is immutable, the string cannot be changed in JavaScript. It is impossible to change a particular character.

Creation of string

By string literal
```
var string name = “string value”;
```
JavaScript
zero or more characters written inside single or double quotes or backticks. The string indexes are zero-based, the first character is in position 0 and the second in 1.

By string object using ‘new’ keyword

var string name = new string (“string value”);

In this, a new keyword is used to create an instance of a string. The string object has some disadvantages, for example, the execution speed is slow.

Now, we can see an example of string creation.

String as Literals

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>String</title>
</head>
<body>
    <h2>String </h2>
    <script type="text/javascript">
    var name ="wlcome vijayakumar"; //literal
    var dept ="CSE"
    document.write(name);
    document.write("He is "+dept+"department");
    </script>
</body>
</html>

Output

String Objects In JavaScript

String as Object

JavaScript String Object is a universal object that is used to store strings. A string is a combination of letters, numbers, special characters (single or double quotations), and arithmetic values.

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>String</title>
</head>
<body>
    <h2>String Object </h2>
    <script type="text/javascript">
        var msg = new String("Welcome to JavaScript"); //String object
        document.write(msg);
        //comparisons of literal and objects
        document.write("<br>");
        var str1 ="String"; //literal way
        var str2 = new String("String"); //object
        var str3 = new String("String"); //object
        (str1==str2)?document.write("Equal"):document.write("Not equal"); // comparisions value
        document.write("<br>");
        (str1===str2)?document.write("Equal"):document.write("Not equal"); // comparisoons type
        document.write("<br>");
        //The comparision of two object
        (str2==str3)?document.write("Equal"):document.write("Not equal");// comparisions value
        document.write("<br>");
        (str2===str3)?document.write("Equal"):document.write("Not equal");// comparisions type
        document.write("<br>");
    </script>
</body>
</html>

Output

String Objects In JavaScript

String Object Properties and Methods

String property

Length property – returns the length of the string.

String Methods

String Methods	Description
1.charAt()	It returns a character at the specified position.
2.charCodeAt ()	It returns the Unicode of a specific character.
3.concat ()	Concatenation joining one or more strings.
4.indexOf ()	The given string or word to find the position of the specified value in a string.
5.lastindexOf ()	To find the last position of the specified value in a string.
6.LocaleCompare ()	Comparing the two words, which is equal means returns 1; it is greater means returns 0, and lesser means returns -1.
7.Match ()	The given string matches the sentence means and returns the position.
8.Replace ()	The specified string will be converted to a new string.
9.Search ()	Search the specific value or string in a given paragraph, and return the position of the match.
10.Slice ()	The given particular index in the index is indexed with a particular index and returns the position of the match.
11.Split ()	It will split a string into an array of substrings.
12.Substr ()	Returns the characters in a string starting at the specified location by a specified number of characters.
13.subString ()	It returns characters from a string between two specified indexes.
14.tostring ()	Returns the value of the specified string object.
15.Trim ()	Eliminates the space between the two ends of a string.
16.toUpperCase ()	It converts a string to uppercase (capitalize) letters.
17.toLowerCase ()	It converts a string to Lowercase letters.
18.valueOf ()	it will display the total string value or primitive value of a string object.

Example of string Property

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>string</title>
</head>
<body>
        <h2>String Length Property</h2>
    <p id="len">Click the button to display number of characters in string is :</p>
    <button onclick="mystr()">Str_len</button>
    <script type="text/javascript">
        var str ="Welcome to JavaScript";
        function mystr() {
            var str ="Welcome to JavaScript";
            document.getElementById("len").innerHTML=str.length;
        }
        document.write("<br>Sting Length :"+str.length);
    </script>
</body>
</html>

Output

String Objects In JavaScript

Example of string Methods

In the below example, all the string methods are included in this example.

To Extract String Characters

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>String</title>
</head>
<body>
    <h2>To extract string character</h2>
    <script type="text/javascript">
        var str1 ="Welcome to JavaScript";
        var str2 ="String Objects";
        var str3 ="Methods"
        document.write("<br>1.charAt() is:"+str1.charAt(3));
        document.write("<br>2.charCodeAt()Method is:"+str1.charCodeAt());
        document.write("<br>2.concat()Method concatinatation method is:"+str2.concat("",str3));//joining tow strings
    </script>
</body>
</html>

Output

String Objects In JavaScript

To Look for a Substring

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>String</title>
</head>
<body>
    <h2>To look for a Substring</h2>
    <script type="text/javascript">
        var str ="JavaScript String Object is a universal object that store string."
        document.write("<br>indexOf()Method find the object word is :"+str.indexOf("object"));
        document.write("<br>lastIndexOf()Method find the object word is :"+str.lastIndexOf("object"));
    </script>
</body>
</html>

Output

String Objects In JavaScript

To Compare a String

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <title>string Methods</title>
</head>
<body>
    <h2>To Compare string</h2>
    <script type="text/javascript">
        //local compare no variables
        document.write("<br>1.localeCompare()Method comparing of India and India is:"+'India'.localeCompare("India"));
        //it will returns zero
        document.write("<br>1.localeCompare()Method comparing of India and India is:"+'Indi'.localeCompare("India"));
    </script>
</body>
</html>

Output

String Objects In JavaScript

To Get a Substring

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <title>string Methods</title>
</head>
<body>
    <h2>To get Substring</h2>
    <script type="text/javascript">
        var str ="JavaScript String Object is a universal object that store string."
        //string slice particular part string or character will be displayed
        document.write("<br>slice()Method slice string is:"+str.slice());
        // if give the value means to display the end posotion
        document.write("<br>slice()Method slice string is:"+str.slice(3,10));
        //substring
        document.write("<br>substr()Method sub string is:"+str.substr(3,15));
        //it diplay the string inbetween the two value
        document.write("<br>substring()Method sub string is:"+str.substring(3,15));
    </script>

</body>
</html>

Output

String Objects In JavaScript

To Change Cases

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <title>String Methods</title>
</head>
<body>
    <h2>To Case Change</h2>
    <script type="text/javascript">
        var str1 ="Welcome to JavaScript";
        var str4 ="WELCOME To JAVASCRIPT";//uppercase
        //upper case and Lowercase
        document.write("<br>toUpperCase()Method is:"+str1.toUpperCase('string','stirngs'));
        document.write("<br>toLowerCase()Method is:"+str4.toLowerCase('string','stirngs'));
    </script>
</body>
</html>

Output

String Objects In JavaScript

To remove white space on both sides

Try it yourself,

<!DOCTYPE html>
<html>
<head>
    <title>string methods</title>
</head>
<body>
    <h2>To remove white Space both sides</h2>
    <script type="text/javascript">
        var str4 ="WELCOME     To      JAVASCRIPT";
        //trim method remove unnecessary spaces
        document.write("<br>trim()Method is:"+str4.trim());
    </script>
</body>
</html>

Output

String Objects In JavaScript

Summary

In this article, we have learned about String Objects, String object Methods, and Properties. I hope this article was helpful to you. Thanks for reading!