Javascript was at first used to embed applets into webpages. Hence the name "Java"Script. Learning JS is really easy, you just need a little experience in HTML.
Go!
To start, we need our HTML document:
<html> <head> <title>JS tester</title> </head> <body> </body> </html>
This is the basic form that we'll use. Now, JS code goes between the <script> tags. The script tags can go either between the head tags or the body. For example, JS in the head elements:
<html> <head> <title>JS tester</title> <script> //Code </script> </head> <body> </body> </html>
See? Now, notice my //Code? The double slashes shows that the string after it is a comment. The web browser that views the page won't process the comment.
Basics
There are many statements that execute things in the browser window. However, there are a few that I want to cover here.
The first is the document.write("String"); statement. That writes the "String" string to the page. Notice that after that statement, I placed a semi-colon. That signals to the web browser to execute the next line of code.
The next is the window.alert("String"); code. This sends the string to the browser and it pops up as a window alert with the exclamation point in the left part.
Lets try this:
<html>
<head>
<title>JS tester</title>
</head>
<body>
<script>
document.write("My first actual JS statement!");
</script>
</body>
</html>
This should write "My first actual JS statement!" to the page.
Now YOU try the window.alert statement. Did it work?
Functions
Functions are containers for JS code. An example:
function new_function() {
//Code
}
Functions can be called to be executed when you use executors like onclick or onload. The executors are placed inside HTML elements like so:
<html>
<head>
<title>JS tester</title>
</head>
<body onload="greetings()">
<script>
function greetings() {
window.alert("Greetings!");
}
</script>
</body>
</html>
When the page loads, a pop up box will show saying "Greetings!". See the executor in the body element?
Variables
Variables are... variable. They can be anything from a object to a string. A variable is declared like so:
var new_variable = "New variable string!";
So now, lets use what we've learned all together:
<html>
<head>
<title>JS tester</title>
</head>
<body onload="say_name()">
<script>
var my_name = "Kewl";
function say_name() {
window.alert("My name is " + my_name + ".");
}
//Look at how I used the window.alert statement. First I said My name is, then I used + to use my variable.
</script>
</body>
</html>
This should say "My name is Kewl."
Now that you've ran this, try building a program that says your name and writes your name to the page. Have fun!
Resources
http://www.w3schools.../JS/default.asp
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