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  1. #1
    Sexiest Man Alive Parms18's Avatar
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    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!
    Parms18

  2. #2
    Perl/Mason Guru Flawless_koder's Avatar
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    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
    ---=| If you're going to buy a pet - get a Shetland Giraffe |=---

  3. #3
    Perl/Mason Guru Flawless_koder's Avatar
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    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 )
    ---=| If you're going to buy a pet - get a Shetland Giraffe |=---

  4. #4
    The doctor is in... silver trophy MarcusJT's Avatar
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    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
    MarcusJT
    - former ASP web developer / former SPF "ASP Guru"
    - *very* old blog with some useful ASP code

    - Please think, Google, and search these forums before posting!


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