Hello World

1) Comments

​

Comments allow you to leave notes to yourself (and others) within your code. Comments don’t get run as part of your program, it’s really handy to be able to do this.

 

The different Coding languages use different methods to declare a line of code a comment, for example:

 

// This is a comment in JavaScript

<!— This is a comment in HTML —>

/* This is a comment in CSS */

 

caveat: https://www.xanthir.com/b4U10 

 

2) Integers

 

An integer is just a whole number any whole number (1,2,3,4…).

 

3) Variables

 

Variables are just a kind of receptacle for a value, be it a numeric value or a piece of text, whatever. If you say “X=2” then “X” is the variable and “2” the value it holds, Refer to “X” in your code and you might as well be writing “2”. Using variables is really common in Coding.

 

4) Conditional Statements

 

For example, in JavaScript, If, Else, Else If and Switch allow you to create conditional statements, sort of like “If there’s whole milk at the shop then buy it, else get semi-skimmed milk”.

 

5) Loops (like For or While loops)

 

Example of a While loop:

 

While loops execute a block of code as long as a specified condition is met.

 

while (i < 10) {

  text += "The number is " + i;

  i++;

}

 

BEWARE!: If you forget to increase the variable used in the condition, the loop will never end. This may crash your program or cause a browser to “hang”, etc.

 

You can make loops conditional, for example:

 

for (i = 0; i < 5; i++) {

  text += "The number is " + i + "<br>";

}

 

i=0 sets up the variable “i” to be “0”, the loops runs as long as “i” is less than 5 and 1 is added to the variable “i” each time the loop runs.

 

In this example

 

Statement 1 sets a variable before the loop starts (var i = 0).

 

Statement 2 defines the condition for the loop to run (i must be less than 5).

 

Statement 3 increases a value (i++) each time the code block in the loop has been executed (increments)

 

6) Nested Statements

 

For example, you can put a load of “if” statements inside an “if” statement. 

 

if (condition1) 

{

   // Code here executes when condition1 is true

   if (condition2) 

   {

      // Code here executes when condition2 is true

   }

}

 

7) Arrays

 

Think of arrays as like filing cabinets where you store a bunch of values. You can even get really fancy and create “multi-dimensional arrays”, which are basically just an array that stores a load of arrays, like a filing cabinet where each file contains another filing cabinet.

 

In javaScript arrays might look similar to these examples:

 

var cars = ["Saab", "Volvo", "BMW"];

var cars = new Array("Saab", "Volvo", "BMW");

 

Don’t overlook the power of these simple code elements, they’re used in everything from database manipulation to games design.

 

8) Functions

 

You can write your own magic words in code!

 

You define what you want to happen when you create the function then, every time you “call” that function by the name you gave it, all the code it contains will run. They’re really, really useful.

 

Here’s an example that uses two number variables (v1 and v2), that are fed in to the function inside those brackets after it’s name (“MyFun”):

 

function myFun(v1, v2) {

  return v1 + v2; // The function returns the product of p1 and p2

}

 

Here “return” means that when you “call” the function in your code you might as well have written the product go the function.

 

One great thing about functions is that, if the value of v1 or v2 is changed elsewhere in your code, the function doesn’t need to be rewritten or updated! It just spits out its result using whatever those new values were. Awesome.

​