Page 207 - Web Applications (803) Class 12
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3.12 FUNCTIONS IN JAVASCRIPT

                 A block of code created specifically to carry out a specific task is referred to as a JavaScript function. If
                 “something” calls a JavaScript function, it will be executed (function call).
                 The function keyword, a name, and then parentheses define a JavaScript function().

                 Syntax:
                    function name(parameter1, parameter2, …………) {
                            // code to be executed
                    }
                   Numerals, underscores, dollar signs, and letters are all permitted in function names (same rules as variables).
                   Parameter names can be included in parenthesis, with commas separating them as shown above.
                   Curly brackets, {}, surround the code that will be executed by the function.

                   The values that the function receives when it is called are known as parameters/arguments for the function.

                 Invoking a function
                 When “something” invokes (calls) the function, the code inside it will run. This happens in the following scenarios:

                   When an event happens (a user clicks a button)
                   When JavaScript code calls (invokes) it

                   Automatically (self-invoked)
                 Example:

                    <html>
                    <body>

                    <h2>JavaScript Functions</h2>
                    <p>This code calls a function which multiplies two numbers</p>

                    <script>

                    function myFunction(p1, p2)               //Function definition
                    {

                      document.write("The product is "+(p1*p2)); //Function body
                    }

                    myFunction(4, 3);                   //Function call
                    </script></body>

                    </html>
                 Output of the preceding program is as follows:














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