undefined returned from function

I solved my issue with the code below but I would still like to know why the above didn't work.

function getIndex(val){        
	for (var x=0; x<jsonFile.Result.Contracts.length; x++){  
        if (jsonFile.Result.Contracts[x].Plan.Identification.PlanNumber == val) {
            var index = x;
          }
  }
  return index;
}

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no such project "893x-3owe34p"

Yes there is. "PlanNumber"
The last one in the Contracts array

or maybe you want to do this

var index = -1;
var proj = "893x-3owe34p";

var item = getIndex(proj)

alert(index);
alert(item);

function getIndex(val) {
  var filteredObj = jsonFile.Result.Contracts.find(function(item, i) {
    console.log(item.Plan.Identification.PlanNumber)
    if (item.Plan.Identification.PlanNumber == val) {
      index = i;
      return item;
    }
  });
  return filteredObj;
}

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https://jsfiddle.net/HainKurt/rbuzLto5/

it sets index  + returns found object...

What I should get back is 5.
If it's a function, how come it can't return the index? Just curious

Or like this - a bit more concise

var proj = "893x-3owe34p";

var filteredObj = jsonFile.Result.Contracts.find(function(item, i) {
  return item.Plan.Identification.PlanNumber == proj
});

if (filteredObj) {
  index = jsonFile.Result.Contracts.indexOf(filteredObj);
  console.log(index);
}

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You can - but you weren't
Your return was inside the find() function block not the getIndex() function block.

find() expects a true / false return based on whether the item was found or not - but this would end up with setting filteredObj to the found item - but you don't do anything with filteredObj and nothing is returned - hence the undefined.

Thanks Guys!