JavaScript Functions
➢A JavaScript function is a block of code designed to perform a particular task.
➢A JavaScript function is executed when "something" invokes it (calls it).
➢A JavaScript function is executed when "something" invokes it (calls it).
EXAMPLE:
function myFunction(p1, p2) {
return p1 * p2; // The function returns the product of p1 and p2
}
return p1 * p2; // The function returns the product of p1 and p2
}
The () Operator Invokes the Function
function toCelsius(fahrenheit) {
return (5/9) * (fahrenheit-32);
}
document.getElementById("demo").innerHTML = toCelsius;
return (5/9) * (fahrenheit-32);
}
document.getElementById("demo").innerHTML = toCelsius;
Local Variables
➢Variables declared within a JavaScript function, become LOCAL to the function.
➢Local variables can only be accessed from within the function.
➢Local variables can only be accessed from within the function.
EXAMPLE:
// code here can NOT use Name
function myFunction(p1, p2) {
let Name = "Sunny";
// code here CAN use Name
}
// code here can NOT use Name
function myFunction(p1, p2) {
let Name = "Sunny";
// code here CAN use Name
}
// code here can NOT use Name
JavaScript Strings
➢A string (or a text string) is a series of characters like "John Doe".
➢Strings are written with quotes. You can use single or double quotes:
➢Strings are written with quotes. You can use single or double quotes:
EXAMPLE:
let Name1 = "Sanvi"; // Using double quotes
let Name2 = 'Sanvi'; // Using single quotes
let Name2 = 'Sanvi'; // Using single quotes
EXAMPLE:
let x = "It's alright"; // Single quote inside double quotes
let y = "He is called 'joshik'"; // Single quotes inside double quotes
let y = 'He is called "joshik"'; // Double quotes inside single quotes
let y = "He is called 'joshik'"; // Single quotes inside double quotes
let y = 'He is called "joshik"'; // Double quotes inside single quotes
➢JavaScript has only one type of numbers.
➢Numbers can be written with, or without decimals:
➢Numbers can be written with, or without decimals:
EXAMPLE:
let x1 = 55.55; // Written with decimals
let x2 = 55; // Written without decimals
let x2 = 55; // Written without decimals
JavaScript Booleans
➢Booleans can only have two values: true or false.
EXAMPLE:
let x = 10;
let y = 10;
let z = 10;
(x == y) // Returns true
(x == z) // Returns false
let y = 10;
let z = 10;
(x == y) // Returns true
(x == z) // Returns false
JavaScript Arrays
➢JavaScript arrays are written with square brackets.
➢Array items are separated by commas.
➢Array items are separated by commas.
EXAMPLE:
const Names = ["Manu", "Sunny", "Joshik"];
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