getElementByTagName function needed

I need to create a text area in which the user will input the auto responder code. I hope everyone knows this. The auto responder code will have a full form code provided by most of the auto responder services like mailchimp, aweber etc.

I need to use getElementByTagName or anything else to extract all the input elements from the pasted code.

For example I w开发者_C百科ill have 3 boxes below this text area, one will have Name field, 2nd will be email field and 3rd will be a box which will add all the hidden fields extracted from the above text area.

Yes, getElementsByTagName exists already.