>I created a simple (I thought) javascript function that would allow a DIV block of collapse and expand. It worked once, but as I simplified it more, it stopped working. I have staring at the code for hours, but can not see why it fails.
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>-- See attachment --
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>Can anyone see where I messed up?
You were making a assignment with the if. Should be:

if (oHeader.style.display === 'block') {
}

FWIW, if you're doing a lot of this type of DOM manipulation take a look at angular....