use existing variable in for loop

Question

Is it possible to leave out the variable assignment from a for loop and do something like this…?

otherVar = 3;

for ( otherVar > 0; otherVar-- )
{
    stuff
}

You can also declare a bunch of vars right in the loop: for(var someVar=0, otherVar=3, yetAnother='bob';yetAnother!==false;someVar++) — Erik Reppen
– Erik Reppen, Commented May 23, 2012 at 3:42

jahroy · Accepted Answer · 2012-05-23 03:26:22Z

16

Yes, but you need to put in the semi-colon:

var otherVar = 3;

for ( ; otherVar > 0; otherVar-- ) {
    doStuff();
}

answered May 23, 2012 at 3:26

jahroy

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Comments

J A · Accepted Answer · 2012-05-23 03:26:15Z

1

Usually While is more popular for this situation (better readability)..

otherVar = 3;

while ( otherVar > 0)
{
   stuff
   otherVar--;
}

answered May 23, 2012 at 3:26

J A

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2 Comments

Essential Over a year ago

Ah, decided to do it your way. Not sure why I was trying to use a for loop. :)

J A Over a year ago

Happy to help:). shorthand for the while condition is while( otherVar-- > 0 ) in case if don't like to use incrementation at the end of the loop. Btw, +1 is a good way to mention that the answer was useful here in SO. Thanks

Sampson · Accepted Answer · 2012-05-23 03:27:18Z

0

You can count down from any arbitrary number:

var counter = 3;
while ( counter-- ) {
  console.log( counter );
}

Which outputs: 2, 1, 0

answered May 23, 2012 at 3:27

Sampson

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1 Comment

Nibin Over a year ago

Just a quick question. Correct me if I'm wrong but the while loop runs till the expression inside the parentheses is true right. when does counter-- become false or true.

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