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JavaScript - String Object


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JavaScript - String Object

Introduction:

In this article I am going to explain about string object and what are the methods are available to perform manipulation on string.

String object in Java Script provides us work with a series of characters. The string object is used to manipulate a stored piece of text. String objects are created with the new keyword.

Syntax for creating string object:

var text=new String(“string”);

Or more simply we can declare string object like this

var text=”string”;

String Objects Properties:

Constructor: It will return the function that created the string object prototype.

Length: Returns the length of the string.

Prototype: Allows us to add properties and method to an object.

String Object Methods:

1.       charAt () : It will return the character at the specified index.

2.       charCodeAt() : It will return the number  which is the  actually the Unicode value of the character at the specified index.

3.       Concat() : It combine the two string into a single string.

4.       indexOf() : Returns the index position of the first occurrence of a specified value in a string.

5.       lastIndexOf() : Returns the last index position of a specified value in a string.

6.       match() : Used to match a given string with a regular expression.

7.       toString() : Returns the string representation of a specified object.

8.       toUpperCase() : Returns the call calling string value to uppercase.

9.       substring() : Returns a extracted substring between two indexes in the string.

10.   toLowerCase() : Returns the calling string value to lowercase.

11.   valueOf() : It returns the primitive value of a specified object.

12.   Split() : It splits the string object into array of two strings by separating the two strings into substrings.

13.   search() : To search a given pattern in a string.

String HTML Wrappers:

These are a list of methods which returns copy of the string wrapped inside the appropriate HTML tag.

1.       big() : It creates a string which is to be displayed in a big font same as it were in a big tag.

2.       blink() : It creates a string which provides the same function as the <blink> tag in that keeps blinking the text contained in tag.

3.       bold(): It creates a string as it were in the <b> tag.

4.       sub() : It is used to displays the string as a subscript same as the <sub> tag .

5.       sup() : It is used to display the string as a superscript same as the <sup> tag.

Example of Length Function in Java Script:

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <script type="text/javascript">

        var countString = "Abhishek";

        document.write("Length of the string is : " + countString.length);

    </script>

</head>

<body>

</body>

</html>

Output will be:  Length of the string is : 8

Example of Split function used in Java Script:

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <script type="text/javascript">

        var myString = "Abhishek";

        var mysplit = myString.split("i");

        document.write("The first element is " + mysplit[0] + "<br />" );

        document.write("The second element is " + mysplit[1]);

    </script>

</head>

<body>

</body>

</html>

 

In this example the split function will break the string into two parts where the i is encountered      Output will be: The first element is Abh,

The second element is shek.

Example of Search Function:

When we have to search that a given expression is available in the given string. If the match was successful then it will return the position where the match was found else it will return -1.

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <script type="text/javascript">

        var myregex = /Monday/;

        var myString = "Today is Monday";

        var IsMatchPosition = myString.search(myregex);

        if (IsMatchPosition != -1) {

            document.write("String matched at position " + IsMatchPosition);

        }

        else {

            document.write("String not matched");

        }

    </script>

</head>

<body>

</body>

</html>

String Replace Function:

String Replace function takes two argument:

1.       Search For: Search for contains what word is going to be replaced.

2.       Replace Text: It contains the words which will replace the Search for Content.

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <script type="text/javascript">

        var day = "Tuesday";

        var OldString = "Today is Monday";

        document.write("Old String is " + OldString);

        var NewString = OldString.replace("Monday", day);

        document.write("<br/>  New String is " + NewString);

    </script>

</head>

</html>

 

Output is:

Example of IndexOf() Function:

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <script type="text/javascript">

        var str = "is";

        var myString = "Today is Monday";

        var indexFound = myString.indexOf(str);

        document.write(indexFound);

    </script>

</head>

<body>

</body>

</html>

In this example I am showing the use of indexOf(), It will show the index where the first match is found.

Conclusion:     From this article you will know about the string functions which are available in Java Script and using these functions what operations can be performed on a given string.


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