# JavaScript Conditionals

• Jun 21, 2002, 06:51
Parms18
JavaScript Conditionals
Okay, I've just finished a big thick book on JavaScript, but unfortunately something wasn't explained to me. I know lost of conditionals, like ==, &&, +=, <=, !=, >=, <, and >, but when I look at advanced scripts I see ++...can someone explain this one to me? I'd also appreciate some sort of list of conditionals, since there are probably others.

Greatly Appreciated!
• Jun 21, 2002, 07:35
Flawless_koder
It's not a conditional test.

It's an arithmatic function called autoincrement ( and hencely autodeincrement )

\$i=5;
\$i++; // return \$i then increment it
++\$i; // increment \$i then return it

thusly if you did:

\$i = 20;
\$d = \$i++; // \$i = 21 and \$d = 20

\$i = 20;
\$d = ++\$i; // \$i = 21 and \$d = 21

The same is true of --

if you want to remember which returns which think of it from left to right. \$d=\$i++; < thus \$d = \$i THEN you increment it. \$d=++\$i < thus \$d = Increment THEN \$i

okie

Hope this helps

Flawless
• Jun 21, 2002, 07:38
Flawless_koder
After thought:

you might have seen this in a for loop

for (\$i=0;\$i<10;\$i++)

ie:
for (starting value; condition to end upon; upon each iteration)

hencely on the first iteration \$i = 0 - since it retruns THEN increments.

This is used less often now as people prefer to use
for (number .. end )
as a sequence system - but this is because they are normally
just caring about the number of times their iteration gets run - rather than the number of the current iteration.

Flawless

( btw - excuse the \$i's - i'm working my *** of in perl modules right now )
• Jun 22, 2002, 07:34
MarcusJT
As well as the ++ (increment) and -- (decrement) operators, there are also may operators for manipulating a variable's value relative to its present variable.

e.g. "tmp *= 2" is the same as "tmp = tmp * 2"

Any good reference on JS or C++ should list and explain all of these operators, such as Microsoft's JScript reference (see my sig).

M@rco