Web Programming and Problem Solving

1. Web Programming and Problem Solving

Nazarbayev University
Lesson
Programming Basics
Presented by Click to enter name

2. Getting Started with JavaScript

Usually, JavaScript is used in web pages… for
now, we will just concentrate on basics of the
language
A JavaScript Interpreter:
http://www.webtoolkitonline.com/javascripttester.html

3. A First Program

Try the following program:
var a;
var b;
var c;
a = 13;
b = 200;
c = a + b;
document.write(c);

4. Values and Variables

In programs, variables are labels that
represent places where data is stored
The data that is stored inside a variable is
called its value
What are the
variables and their
values in this
program?
var a;
var b;
var c;
a = 13;
b = 200;
c = a + b;
document.write(c);

5. Declaration

To tell the computer to set aside storage
space for a variable, you should declare the
variable
In JavaScript, you
declare variables
using the var
keyword
var a;
var b;
var c;
a = 13;
b = 200;
c = a + b;
document.write(c);

6. Assignment

To change the value stored in a variable, you
assign it a new value using the equals sign
var a;
var b;
var c;
Examples of
assignments
a = 13;
b = 200;
c = a + b;
document.write(c);

7. Expressions

Expressions are things that can have a value
Examples:
Variables
Numbers and other
literals
Expressions joined
together by operators
(e.g., +, -, *, /)
What expressions
do you see in this
program?
var a;
var b;
var c;
a = 13;
b = 200;
c = a + b;
document.write(c);

8. Statements

Statements are the elements in code that
perform individual tasks in sequential order
Think “a line of code”
Often end with a semicolon
Examples:
Declarations
Assignments
Function calls
What are the statements
in this program?
var a;
var b;
var c;
a = 13;
b = 200;
c = a + b;
document.write(c);

9. Working with Numbers

Arithmetic operations (+, -, *, /) can be used
Order of operations: * and / take precedence
over + and –
Exercise: What values do these produce?
100 + 4 * 11
(100 + 4) * 11
115 * 4 – 88 / 2

10. Exercise 1

Add code to the following program to convert
Fahrenheit to Celsius using the formula:
(F – 32) * 5/9 = C
var fahr = 100;
var cels;
// add your code here
document.write(cels);

11. Exercise 2

Add code to the following program to
calculate the average of a, b, and c
var
var
var
var
a = 10;
b = 20;
c = 25;
avg;
// add your code here
document.write(avg);

12. Challenge Exercise

Add code to the following program to
calculate both roots of a quadratic equation
var
var
var
var
a =
b =
c =
x1,
2;
-4;
-6;
x2;
var d = ???;
var sqrtd = Math.sqrt(d);
x1 = ???;
x2 = ???;
document.write(x1 + ", " + x2);