javasccript find element in array of object

Question

Let's say I have an array of objects and one of the properties of each object is TheID. Something like this:

TheArray[0].TheID = 34;
TheArray[1].TheID = 2352;
...

I'm looking to return the index of the array that contains the property TheID I'm looking for.

I have a classic for-loop:

for (i = 0; i < TheArray.length; i++) {
   if (TheArray[i].TheID = MagicNumber) { var TheIndex = i; } 
}
retun TheIndex;

This works but it still has to loop through the entire array, even after it found TheIndex.

How do you stop the loop after the it found TheIndex?

Thanks.

Throw it into a function, then return the variable. It'll drop out of the loop. Or use break. — kevingreen
– kevingreen, Commented Nov 22, 2011 at 21:43

Li0liQ · Accepted Answer · 2011-11-22 21:45:02Z

3

You could use break to leave the loop:

var TheIndex;
for (var i = 0; i < TheArray.length; i++) {
   if (TheArray[i].TheID == MagicNumber) {
      TheIndex = i;
      break;
   } 
}
return TheIndex;

answered Nov 22, 2011 at 21:45

Li0liQ

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Jonathan M · Accepted Answer · 2011-11-22 21:46:00Z

0

if (TheArray[i].TheID = MagicNumber) { return i; }

answered Nov 22, 2011 at 21:46

Jonathan M

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mattacular · Accepted Answer · 2011-11-22 22:01:50Z

0

Break; or return; within a loop to stop it once you have found what you are looking for. There is no other way to search arrays/objects for specific property values. You could consider re factoring your code entirely to avoid unnecessary performance sinks like this but that isn't always feasible.

answered Nov 22, 2011 at 22:01

mattacular

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epeleg · Accepted Answer · 2012-07-18 20:39:33Z

0

Even though this is from a while ago, another alternative that might be useful if you do many such searches would be to loop once an index based on your search criteria.

e.g. do this once:

var idToIdx={};
for (var i = 0; i < TheArray.length; i++) {
   idToIdx['I'+TheArray[i].TheID] = i
   } 
}

and then just use for idToIdx['I'+ MagicNumber] as many times as you need.

answered Jul 18, 2012 at 20:39

epeleg

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