# Vector datatype checking?

**URL:** <https://forum.kirupa.com/t/vector-datatype-checking/320631>\
**Category:** flash\
**Created:** [March 29, 2011, 12:52am UTC](https://forum.kirupa.com/t/vector-datatype-checking/320631 "2011-03-29T00:52:47Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Poco](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@Poco](https://forum.kirupa.com/u/Poco)\
**Post date:** [March 29, 2011, 12:52am UTC](https://forum.kirupa.com/t/vector-datatype-checking/320631/1 "2011-03-29T00:52:47Z")

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Hi,

How exactly does the datatype checking of Vector work? The documentation states that an exception occurs at runtime if there was a wrong argument pushed to the Vector. However if I try this:

```auto

private var numberVector:Vector.<Number> = new Vector.<Number>();
...
numberVector.push(thumbnailInstance)

```

And then I trace it, I get NaN (cos it is a thumbnail 🙂 ). However, no exception is being thrown. What am I doing wrong?  
Thanks!

P.