Page 307 - Web Applications (803) Class 11
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4.13 STRING OPERATIONS
You already know that concatenation is performed by placing a + sign between two strings. You can also use various
string methods in JavaScript to work with strings:
Method/ Description Example
Property
length Returns the string’s length. document.write(“Constantinople”.length)
Output: 14
substring It extracts the substring using the starting and ending str1 = “Pineapple is very tasty!”;
positions as parameters. If you leave the ending position document.write(str1.substring(7,20))
blank, the string will be extracted from beginning to Output: le is very ta
end.
search It returns the position of the first match, -1 otherwise. text = "I am studying JavaScript";
document.write(text.search("studying"))
Output:5
document.write(text.search("Math"))
Output: -1
4.14 TYPE CONVERSIONS IN JAVASCRIPT
When two distinct types of data are used in an expression, JavaScript automatically converts the data and evaluates
the expression. This action is called type conversion. In JavaScript, there are two ways to convert the type:
Type Conversion
Implicit Type Conversion Explicit Type Conversion
Implicit Type Conversion
When an expression is evaluated and two different types are given that are incompatible to perform the operation,
JavaScript automatically converts them. The following are some examples of implicit conversions:
Ð ÐIf one value is a number and the other is a string, the expression turns the string to a number and performs the
arithmetic operation. For example, 12 * “5” returns the number 60, and 2 – “5” returns -3.
Ð ÐIn arithmetic operations, if a value is null, it is converted to the integer value 0. The outcome of null + 8 is 8, for
example.
Ð ÐIn an arithmetic operation, if one value is Boolean, it is converted to 0 or 1 depending on the provided value. True
+ 6 yields a result of 7, while false+8 yields a value of 8.
Ð ÐIf the value cannot be translated to another type, it is returned as NaN (Not a Number).
Explicit Type Conversion
The developer does this type of conversion by utilizing the built-in type conversion methods.
Introduction to Dynamic Websites Using JavaScript 305

