JavaScript Reference: Functions

// This function takes in a parameter x and returns x cubed:
function cube( x ) {
	return x*x*x
}
	
// This function does not require a parameter, and creates a pop-up when called:
function getInfo( ) {
	prompt( "What is your name?" )
}

// This function takes in two parameters, and prints their sum/concatenation to the terminal:
function printSum( x,y ) {
	console.log( x+y )
}

// This function takes in a number x, and returns (x+1)^3 by calling the cube function defined above:
function plusOneCube( x ) {
	var y = cube( x + 1 )
	console.log(y)
}

function cube( x ) {
	return x*x*x
}
	
var twoCubed = cube(2)	// twoCubed now has value 8	

// A function may also return a boolean value, true or false. The following example creates a function that returns true if a value is found in an array:

var myArray = [1,2,3,4,5,6,7,8,9,10]

function inTable( a, x ) {
	var in = false	
	for ( i = 0; i < a.length; i++ ) {
		if ( a[i] === x ) {
			in = true;
			break;
		}
	}
	return in	
}

inTable( myArray, 6 )	// would return true
inTable( myArray, 11 )  // would return false

function firstLetter( s ) {
    return s.charAt(0)
}

console.log("The first letter of dog is "+firstLetter('dog'))