JavaScript: Functions

Table of Contents

First things first

Sorry for 2 days without uploading, I have no internet due to the provider being an idiot.

Functions

Functions: Functions are one of the fundamental building blocks in JavaScript. A function in JavaScript is similar to a procedure—a set of statements that performs a task or calculates a value, but for a procedure to qualify as a function, it should take some input and return an output where there is some obvious relationship between the input and the output. To use a function, you must define it somewhere in the scope from which you wish to call it.

function name() {
 do;
 do;
}

// Call the function
name();

Challenge

https://stanford.edu/~cpiech/karel/ide.html

Help Karel to go to top right: 15x15

/**
 * Welcome to the Stanford Karel IDE.
 * This is a free space for you to 
 * write any Karel program you want.
 **/
function main(){
   //your code here
   move14();
   turnLeft();
   move14();
}

function move14() {
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   move();
   }

Make a diagonal beeper

/**
 * Welcome to the Stanford Karel IDE.
 * This is a free space for you to 
 * write any Karel program you want.
 **/
function main(){
   //your code here
   putBeeper();
   toTheSpot();
   toTheSpot();
   toTheSpot();
   toTheSpot();
}

function toTheSpot() {
   move();
   turnLeft();
   move();
   putBeeper();
   left3Times();
   }
   
function left3Times(){
   turnLeft();
   turnLeft();
   turnLeft();
   }

Have Karel to make a chessboard:

/**
 * Welcome to the Stanford Karel IDE.
 * This is a free space for you to 
 * write any Karel program you want.
 **/
function main(){
   //your code here
   left2Right();
   left2Right();
   turnUpRight();
   right2Left();
   right2Left();
   turnUpLeft();
   left2Right();
   left2Right();
   turnUpRight();
   right2Left();
   right2Left();
   turnUpLeft();
   left2Right();
   left2Right();
   putBeeper();
}

function left2Right() {
   putBeeper();
   move();
   move();
   }

function turnUpRight() {
   putBeeper();
   turnLeft();
   move();
   turnLeft();
   }
   
function right2Left() {
   move();
   putBeeper();
   move();
   }

function turnUpLeft() {
   turnRight();
   move();
   turnRight();
   }

Parameters and Arguments

function exampleFunction(argument) {
 var cost = argument;
 // do something with cost
}

exampleFunction(argument);

Challenge

Create a function that buy bottles from argument based on money it have.

var startMoney = 10
var bottleCost = 1.5

function buyBottles(bottles) {
 var leftMoney = startMoney - (bottles * bottleCost);
 alert("You bought " + bottles + " bottles, and have " + leftMoney + "$ left");
}

buyBottles(3);

In this challenge, you are going to create a function that tells us how many days, weeks and months we have left if we live until 90 years old.

function lifeInWeeks(age) {
    
/************Don't change the code above************/    
    
    //Write your code here.
    var monthsLeft = (90 - age) * 12;
    var weeksLeft = (90 - age) * 52;
    var daysLeft = (90 - age) * 365;
    
    console.log("You have " + daysLeft + " days, " + weeksLeft + " weeks, and " + monthsLeft + " months lefts.")
    
    
/*************Don't change the code below**********/
}

Outputs and return value

function exampleFunction(number) {
 return number + 1;
}

var newNumber = exampleFunction(number);

Challenge

Make a BMI calculator.

         Weight(kg)
BMI =  --------------
        Height^2(m^2)

//Create your function below this line.
//The first parameter should be the weight and the second should be the height.
function bmiCalculator(weight, height) {
    var bmi = weight / (height * height);
    return Math.round(bmi)
}


/* If my weight is 65Kg and my height is 1.8m, I should be able to call your function like this:

var bmi = bmiCalculator(65, 1.8); 

bmi should equal 20 when it's rounded to the nearest whole number.

*/

Other options

function bmiCalculator(weight, height) {
    var bmi = weight / (Math.pow(height, 2));
    return Math.round(bmi)
}