Javascript cheatsheet

Javascript function example

var isEven = function(number) {
    if(number%2===0)
        return true;
    else
        return false;
};
console.log(isEven(9));

Javascript for loop example

for (var counter = 1; counter < 11; counter++) {
	console.log(counter);
}

Javascript while loop example

var loop = function(){
    var i=0;
	while(i<3){
		console.log("I'm looping!");
		i++;
	}
};

loop();

Javascript switch example

var answer = prompt("Enter a letter here!");

switch(answer) {
  case 'a':
    console.log("a");
    break;
  case 'b':
      console.log("b");
      break;
  default:
    console.log("not a, not b, some other letter");
    break;
}

Javascript array example

var languages=["php","java","python","javascript","c++"];
for(var i=0; i<languages.length; i++)
{
	console.log(languages[i]);
}

Javascript object examples

var BMW = {
    cost:"too much",
    speed:220,
    country:"Germany"
}

var Ford = new Object();
Ford.cost = "OK";
Ford.speed = "210";
Ford.country = "USA";

Javascript object with function in it

var bob = new Object();
bob.age = 30;
bob.setAge = function (newAge){
  bob.age = newAge;
};

bob.getYearOfBirth = function () {
  return 2013 - bob.age;
};
console.log(bob.getYearOfBirth());

Javascript class object example

function StudentReport() {
    var grade1 = 4;
    var grade2 = 2;
    var grade3 = 1;
    this.getGPA = function() {
        return (grade1 + grade2 + grade3) / 3;
    };
}

var myStudentReport = new StudentReport();

for(var x in myStudentReport) {
    if(typeof myStudentReport[x] !== "function") {
        console.log("Muahaha! " + myStudentReport[x]);
    }
}
console.log("Your overall GPA is " + myStudentReport.getGPA());

Javascript Cash Register example

function StaffMember(name,discountPercent){
    this.name = name;
    this.discountPercent = discountPercent;
}

var sally = new StaffMember("Sally",5);
var bob = new StaffMember("Bob",10);

// Create yourself again as 'me' with a staff discount of 20%
var me = new StaffMember("Peng",20);

var cashRegister = {
    total:0,
    lastTransactionAmount: 0,
    add: function(itemCost){
        this.total += (itemCost || 0);
        this.lastTransactionAmount = itemCost;
    },
    scan: function(item,quantity){
        switch (item){
        case "eggs": this.add(0.98 * quantity); break;
        case "milk": this.add(1.23 * quantity); break;
        case "magazine": this.add(4.99 * quantity); break;
        case "chocolate": this.add(0.45 * quantity); break;
        }
        return true;
    },
    voidLastTransaction : function(){
        this.total -= this.lastTransactionAmount;
        this.lastTransactionAmount = 0;
    },
    // Create a new method applyStaffDiscount here
    applyStaffDiscount: function(employee){
        this.total = this.total * (1-employee.discountPercent/100);
    }
    
};

cashRegister.scan('eggs',1);
cashRegister.scan('milk',1);
cashRegister.scan('magazine',3);
// Apply your staff discount by passing the 'me' object 
// to applyStaffDiscount
cashRegister.applyStaffDiscount(me);

// Show the total bill
console.log('Your bill is '+cashRegister.total.toFixed(2));