Beginner javascript: How to use arrays and functions. Includes task.

This tutorial is aimed at beginners who are just starting to learn Javascript or any other programming language. The tutorial will consist of a couple of paragraphs explaining what a function is, what an array is and show an example of how they can be used.

There will also be a small programming task near the end to help you improve your skills, so make sure you read carefully! Lets get started.

Part 1: What is an array

As a programmer you will need to use arrays regularly. They are similar to variables in that they are used to store a value of some description. However, unlike a variable an array can hold multiple values. And they do so in a structured format.

Each value within an array is referred to as an array element and has an index, or ID,  number associated with it. You can access these individual values by using the index assigned to them. As a final note, remember that the indexing is zero-based, meaning that the index starts at 0 rather than 1.

Below is some simple code which shows how to create an array, then assign some values to it.

var classMates=new Array();

classMates[0]="Dave";
classMates[1]="Sam";
classMates[2]="John";
classMates[3]="Kate";

An example of how you could use this data:

alert(classMates[3]);

Part 2: What is a function

In programming terms a function is a named piece of code which performs a specific task, such as multiplying a number or many other calculations.  The code contained within a function will only run when called, or when triggered by an event. You can pass values (known as parameters, or arguments)  into functions, which can then be used to carry out calculations before being returned.

It’s a simple concept to understand, and i dont believe it requires any more explanation.

How to create a function in javascript:

function alertMsg()
{
alert("Hello");
}

And a function that accepts parameters:

function multiply(a,b)
{
return a*b;
}

alert(multiply(5,10));

Part 3: Programming task

Create a function called ‘dayName’ that accepts a number and returns the day of the week based on that number. Details are below

1. Day 1 – Monday, Day 2 – Tuesday, Day 3- Wednesday and so on.
2. The function should first of all create an array.
3. For the purpose of this tutorial you should then store the day names in this array.
4. Use the alert function to display the result once complete.

It’s a pretty simple problem, but it should help you remember what you have learned. If you like the format of this tutorial please leave a comment and i will consider writing more like this.

The solution is hidden below and can be expanded when you are ready

• Solution

  function dayName(day)
  {
  var daynames=new Array(); 
  
  daynames[1]="Monday";
  daynames[2]="Tuesday";
  daynames[3]="Wednesday";
  daynames[4]="Thursday";
  daynames[5]="Friday";
  daynames[6]="Saturday";
  daynames[7]="Sunday";
  
  return daynames[day];
  }
  
  alert(dayName(3));

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