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eloquent javascript

Posted on 2013-06-03
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Last Modified: 2013-06-06
What is the best (i.e. most elegant, concise, readable, beautiful, meaningful, expressive, 31337, etc) way of doing error checking on a long string of functions where each one depends on the one before it?

For example, I have a function called findShift(id) which returns an object if the object isn't found, it returns null. I want to access one of the parts of that object.

var worker = findshift(id).worker.lastname;

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The problem is that if findshift() returns null, then I get a javascript error about how it can't get the .worker property of null. The same goes if the worker property is null and lastname is null. What I really want is for the whole thing to just assign null if any part of the chain is null. One option is the following:

var worker = finshift(id) && findshift(id).worker && findshift(id).worker.lastname;

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but that requires me to run the findshift() function three times, which might be expensive. Another option is this:

var lastname = null;
var worker = null;
var shift = findshift(id);
if (shift) {
    worker = shift.worker;
    if (worker) {
        lastname = worker.lastname;
    }
}

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but I find that to verbose and klunky. Is there a better way to do this? Is Try/Catch the solution?
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Question by:mankowitz
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3 Comments
 
LVL 11

Expert Comment

by:MajorBigDeal
ID: 39217764
if (shift  = findshift(id) == null) return;
if (worker = shift.worker == null) return;
if (lastname = worker.lastname == null) return;
// All data available here
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LVL 11

Accepted Solution

by:
MajorBigDeal earned 2000 total points
ID: 39217769
if (shift = findshift(id)) {
   if (worker = shift.worker) {
      if (lastname = worker.lastname) {
         // All data available here
      }
   }
}
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LVL 11

Expert Comment

by:MajorBigDeal
ID: 39226601
I don't know that this is the most elegant way but I think it is readable!
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