Here is what this part of the tutorial covers:
Some programming basics
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program, you may need to “view source” for all the
code to be visible. To be sure you can see all of the
original article, view it in the archives — it will
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Although they have similar names, they are very
different. Java is a compiled language with modules
that load into your browser from a source external to
interpreted language and is almost always an integral
part of the web page source code.
“Compiled language” means the source code of the
program is translated (compiled) into machine-language
(composed only of 0’s and 1’s) before use. When it is
time to run the program, the translated version is
used by the computer instead of the original source
code. Unless you are the programmer, you might never
see the source code of the program you are using.
“Interpreted language” means when it loads a page, the
browser’s interpreter uses the original source code
and translates it into machine language. The
translation is stored in the browser’s memory ready
to run all or portions of it as appropriate. When the
browser window gets ready to load a different web
Note: Some browsers will display only the active source
code when you “view source”. In other words, you
see only the source code that is actually being used
to display the page at the time you are viewing it.
If you suspect your browser is “censoring” parts of
the source code on a particular page, you can use
Master Snooper. Master Snooper shows you all of the
code in its glory or lack thereof. Just go to
and type in the URL of the web page. (Master Snooper
is also good to see how framed, doorway, and
redirection pages are built, because it shows you
only the source code rather than drawing the display
or getting itself redirected.)
<!– programmer comments can go here
// programmer comments can go here –>
Notice the characters
<input type=”submit” onClick=”do_some_function()”>
When someone visits a web page, it loads into the browser. The HTML is converted into a visible display.
Some programming basics
(1) any that must execute before the entire page has
finished loading, such as code that immediately
determines what kind of browser the visitor is
(2) functions (we’ll describe what they are and other
stuff about them in a later part of this series)
that are called within the <body…> tag.
Oftentimes, it won’t matter whether the program code is above or below the <body…> tag. Many programmers, this author included, usually opt for the “above” position. It helps keep all or most of the program code in one place rather than scattered about.
How to make your program remember things
In order to store stuff in memory and access it later, that memory spot must have a name. The memory spot, itself, is called a “variable” because the contents of the memory spot can change.
To declare that a variable exists and give it a name, you type something like
which creates a variable called “blahblah” where you can store stuff.
To store something into that memory spot, you type something like
blahblah = 5;
and the number “5” is stored in (assigned to) that memory spot.
You can also do all the above in one line, if you want, by typing
var blahblah = 5;
However, once a variable name has been declared, don’t declare it again. If, later on in the program, you want to change the contents of the variable “blahblah”, do it as a simple assignment statement, like
blahblah = 4;
To access what you have stored in a variable (the value you assigned to it), you either have to print it (have it show up on your web page) or assign it to another variable. To print it to your web page, you type
and, when interpreted and executed, that program line will print the value of “blahblah” on your web page.
Here it is, all put together
var blahblah = 5;
The above demonstrates a simple use of a variable. Other uses (described in a later part of this series) include doing mathematical calculations, manipulating strings of characters, storing form field contents, and having your program make decisions based on what a variable contains.
Using strings of characters
Strings of characters need to be enclosed between either apostrophes (‘) or quote marks (“).
Whichever character you choose, it must be used both at the beginning and at the end of the string.
If you have one or more apostrophes within your string, it makes good sense to choose quote marks to contain the string. Example:
On the other hand, if you have one or more quote marks within your string, it makes sense to enclose it within apostrophes, like this:
‘He said, “hot”.’
A special situation arises when you have a string with both an apostrophe and a quote mark within it. In that case, you put a backslash character in front of each occurrence of the character that encloses the string. For example, the string of characters
He said, “I’m hot.”
can be enclosed within apostrophes as
‘He said, “I\’m hot.”‘
or within quote marks as
“He said, \”I’m hot.\””
The backslash tells the browser’s interpreter to treat the character following the backslash as a literal character rather than an “end of string” marker. Once the interpreter has done that, it discards the backslash from the string.
(If you want to use a backslash in a string, you must use two of them in sequence — the browser will discard the first one.)
var hotstuff = ‘He said, “I\’m hot.”‘;
This article has reached its length limit.
The next article in this series will describe useful things to do with variables and will also describe functions and how to call them.