I am rather new to JavaScript and am in need of some major help. I do not have the time or even the knowhow to get this done. To me, it doesn't sound all that difficult to do, but I don't know where to start.

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I need a small form field, that when submitted, checks to see if that number is in the list of numbers that we have been set aside. (the list of numbers can be in the code, or in a separate doc)

If it returns "false", then a small div id#false in my html gets its CSS property set to "display:block;"

If returned "true", then a different div id#true in my html gets its CSS property set to "display:block;"

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Here is why I am trying to do this.
The idea is that I have a string of numbers sent out to customers. These customers go back to the website and enter in their number. If the number matches the ones set aside, then they get a special message. If not, they get another.

Even just a little help on this would be awesome.
And Thank You in advance.