The Basics

You have already seen the mandatory Hello World program - so no need to repeat that here. From now one we will be concentrating one stuff inside the script tag. So when I say
alert("Hello World")
I mean the full HTML file with the 'alert("Hello World")' text inside the script tag. But if you want to try the code in the T-Box, you just have to type alert("Hello World") and not the full HTML content.

Writing Text

Wondering how to write a the string to the HTML area in the window rather than pop up a message box? This code will do the trick.

document.write("Hello World")

Be careful with this. Put it after the the <body> tag like this...

...
</head>
<body>
<script language="javascript">
document.write("Hello World")
</script>
...

If it is given before the body tag, a new page will be created with the 'Hello World' text. This will not work with the T-Box. T-Box will make a new page with the given text. Try it out if you must. Just click the 'Back' button to come back.

Before doing anything with this, I have to warn you that this is an old method - I will NOT recommended its use. If you have to write text into a page use innerHTML or other DOM functions.

Comments

Comment is what a programmer will enter into the source code to make the source more understandable. They are ignored by the interpreter. It is a good idea to explain what you are doing using comments - this makes the code more readable.

There is two types of comments in JavaScript...
// - The Line Comment
/* */ - Block Comment

Example

//This is a single line comment
/* This is a block comment. 
This will comment out every 
thing from the beginning
to the end */

Semi-colon

Semi-colons are not a must but it can be used to separate multiple statements on the same line. It is recommended that you use ';' at the end of all lines.

Example

i=0;i++;

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Comments

Frank at 20 Aug, 2009 05:03

Above the text box above, you've written, "...This is an old method - I will NOT recommended its use." I suggest changing this (to correct the grammar) to "I will NOT recommend its use."

Reply to this.

Frank at 20 Aug, 2009 05:04

...Wow. Great job on my part. I mean to say, "Above the test box above...".
(Head bonk bonk bonk bonkkity bonkkity)

Reply to this.

Comment Formating : HTML tags a, strong, em, b, i, code, pre, p and br allowed. Other tags will be shown as code(< will become <). Urls, Line breaks will be auto-formated.

The Basics

Writing Text

Comments

Semi-colon

Comments

JS Basics

Popular Pages

OpenJS

document.write("Hello World");