incrementing javascript loop use i++ or ++i

crmpicco · April 5th, 2006, 06:38 AM

Code:

for (i=0; i<iNoOfOpts; i++)
{
    ///
    // code
    ////
}

Code:

for (i=0; i<iNoOfOpts; ++i)
{
    ///
    // code
    ////
}

when writing a js incrementing loop, should i use option 1 or 2, either, i++ or ++i?

Picco

www.crmpicco.co.uk
www.ie7.com

ChrisScott · April 5th, 2006, 10:12 AM

Depends on what you are trying to do - ++i increments i before you use it, i++ increments i after you use it.

richard.york · April 6th, 2006, 03:04 PM

In other words.. if I were to write:

Code:

<script type='text/javascript'>

    $i = 0;
    alert('The value of $i is ' + (++$i)); //Outputs 1

    // Value of $i is now 1

    $i = 0;
    alert('The value of $i is ' + ($i++)); //Outputs 0

    // Value of $i is now 1

</script>

++$i increments the value before the value is inserted. $i++ increments the value after the value is inserted. You won't notice the difference between the two unless you're doing an increment operation as part of an expression.

Regards,
Rich

--
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crmpicco · April 12th, 2006, 05:29 AM

Code:

for (var i = 1; i < 8; i++) 
{

still on the same subject, ive seen loops written like this above and below. are there any performance reasons here?

Code:

for (i = 1; i < 8; i++) 
{

thanks.

picco

www.crmpicco.co.uk
www.ie7.com

kaos_frack · May 11th, 2006, 01:39 AM

Quote:

quote:when writing a js incrementing loop, should i use option 1 or 2, either, i++ or ++i?

Code:

for(var i=0; i<iNoOfOpts; ++i)

is the same as

Code:

for(var i=1; i<iNoOfOpts; i++)

Quote:

quote:are there any performance reasons here?

i don't know whether there are performance reasons
but there might be memory differences
cos in the first example ("var i=1") the variable 'i' is
declared as local and in the second it becomes global