String object works with series of characters. It is used to store and manipulate text.
There are two ways to create string in JavaScript:
- String literal.
- Using new keyword.
String literal
By using double quotes string literal is created.
Syntax
var stringname="string value";
Example
<!DOCTYPE html>
<html>
<body>
<script>
var str="Hello String Literal";
document.write(str);
</script>
</body>
</html>
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Output
Using new keyword
Syntax
var stringname=new String("new keyword")
Example
<!DOCTYPE html>
<html>
<body>
<script>
var stringname=new String("Hello String");
document.write(stringname);
</script>
</body>
</html>
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Output
String properties
There are list of properties of string object and there description.
- constructor.
- length.
- prototype.
Constructor- It returns a reference to the string function that created the object.
Syntax
Length-It returns the number of characters in a string.
Syntax
Prototype- It allowed to add properties and method to any object (Number, Boolean, string, and data etc.).
This is global property which is available most of the objects.
Syntax
object.prototype.name = value
There are methods also available in JavaScript string:
| Methods |
Description |
| charAt(index) |
It returns the character at the given index. |
| concat(str) |
It merges the text of two string and returns new string. |
| indexOf(str) |
It returns the index position of the given string. |
| iastindexOf(str) |
It returns the last index position of the given string. |
| match() |
It is used to match regular expression against a string. |
| tolowercase() |
It is used to return given string value converted to lower case. |
| touppercase() |
It is used to return the given string value converted to uppercase. |
| valueOf() |
Returns the primitive value of the specified object. |
charAt()
It is a method that returns the character from specified index.
<!DOCTYPE html>
<html>
<body>
<script>
var str = new String( "Hello" );
document.writeln("str.charAt(0) is: " + str.charAt(0));
document.writeln("<br />str.charAt(1) is: " + str.charAt(1));
document.writeln("<br />str.charAt(2) is: " + str.charAt(2));
document.writeln("<br />str.charAt(3) is: " + str.charAt(3));
document.writeln("<br />str.charAt(4) is: " + str.charAt(4));
</script>
</body>
</html>
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concat(str)
This method add two or more string and return a new string.
<!DOCTYPE html>
<html>
<body>
<script>
var x="Hello";
var y="World";
var z=x+y;
document.write(z);
</script>
</body>
</html>
Try Now
Here another example of conct(str)
<!DOCTYPE html>
<html>
<body>
<script>
var a = new String( "Hello" );
var b = new String( "Friends" );
var c = a.concat( b );
document.write("Concatenated String : " + c);
</script>
</body>
</html>
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indexOf(str)
String indexOf(str) method returns the index position of the given string.
<!DOCTYPE html>
<html>
<body>
<script>
var x="Tutorial provide by tutorialandexample";
var y=x.indexOf("by");
document.write(y);
</script>
</body>
</html>
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lastindexOf(str)
String lastIndexOf(str) method returns the last index position of the given string.
<!DOCTYPE html>
<html>
<body>
<script>
var x="Tutorial provide by tutorialandExamole";
var y=x.lastIndexOf("by");
document.write(n);
</script>
</body>
</html>
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match()
<!DOCTYPE html>
<html>
<body>
<script>
var str = "To more detail, see Chapter 2.5.4.1";
var re = /(chapter \d+(\.\d)*)/i;
var find = str.match( re );
document.write(find );
</script>
</body>
</html>
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toLowerCase()
It returns the given string in lowercase letters.
<!DOCTYPE html>
<html>
<body>
<script>
var x="HELLO WORLD";
var y=x.toLowerCase();
document.write(y);
</script>
</body>
</html>
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toUpperCase()
It returns the given string in uppercase letters.
<!DOCTYPE html>
<html>
<body>
<script>
var x="hello world";
var y=x.toUpperCase();
document.write(y);
</script>
</body>
</html>
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valueOf()
It returns the primitive value of a string object.
<!DOCTYPE html>
<html>
<body>
<script>
var str = new String("Hello world");
document.write(str.valueOf( ));
</script>
</body>
</html>
Try Now
