Can a javascript regular expression help clean up these odd formats?

I found that only one format actually causes problems with the subsequent calculation:

4' .5"

I was having a lot of trouble understanding this line....

$in = parseInt($y[1].trim().substring($y[1]-1)) || '0';

so I broke it down....

var splitit = zheight_feet_and_inches.split("'");
var inchside1 = splitit[1];
var inchside2 = inchside1.trim();
var inchside3  = inchside2.substring(inchside2 - 1);
var inchside4 = parseInt(inchside3);

.....and found I was always getting an NaN value in inchside4 when this was called

parseInt(inchside4)    --   The value of inchside3 at this point is .5".

Can you help me figure out what I am doing wrong?


Thanks!

sorry, typo,  should have said...

.....and found I was always getting an NaN value in inchside4 when this was called

 parseInt(inchside3)    --   The value of inchside3 at this point is .5".

parseInt()  on the right side of the split was a bit of a red herring, but that was my own fault.  I should have mentioned I needed to convert the formats to total inches.

Splitting on the apostrophe was still key, though.   Then I just had to use the substring function to remove the quotes from the right side and use the Number function to add left and right sides back together for total inches.   Just a variation of what Steve said in the first place.

Steve would have received all the points, but I think Kravmir 's points were valid, and helped me stop trying to make Steve's code work as it was and rethink the problem.

Tempted to give a B instead of an A because neither expert mentioned whether or not a regular expression would have been helpful here.
But that is a little nitpicky, and together they both did help me solve the problem. so an A it is.

I am assuming once I click submit, I can allocate the points as I see fit and they won't automatically be split 50/50.  

Let me apolgize in advance if that is not the case.

RE: Using regex, I think that would have been more complicated.  Because you're dropping the decimal portions, you would end up with a conditional replacement for something like 5' .4".  You would have to replace just those instances with "0", where all the others are being replaced with "whatever comes before the decimal".  At the least, you would have needed a series of two replacements - one for the "normal" fit, and a second for the edge case.

In the replace() method for strings in JS you can use a function as the replacement instead of a string which would allow this to be done using a single regular expression, however, in this case it's more efficient to just split the string in the first place.

Instead of using parseInt() it might actually be better to use parseFloat() and then Math.floor() or Math.round().

function pretty($x) {
  var $y = $x.split(/'\s*/),
      $ft = parseInt($y[0],10),
      $in = Math.floor(parseFloat($y[1]));
  return $ft + "'" + $in + '"';
}

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P.S. Please don't give a lower grade when you can post a reply asking for further clarification on some point. Thank you for not downgrading our responses this time.