Understanding the Document Object Model - 13

Thanks for this video, it explains a lot. 

Bob, another option to window.onload event would be to declare the JS file at the bottom of the HTML page. In that case first DOM will get loaded and then JS. I'm not sure whether its a right approach, but I have seen many HTML pages with JS declared in the bottom half. Can you please clarify on this?

HonraoPrasad, its good idea to put any other script or style below html, because to increase performance of the page loading, such that when page gets loaded it can then be configured to.

Re-opening this closed thread ...

Thank you Bob,

I have a question.

  document.getElementById('clickMe').onclick = runTheExample;

//why is runTheExample, not runTheExample()?

When should I put a (), and when I shouldn't put () ?

Thank you!

Best,

Yumiko

@Yumikokk: Great question.  The open-close parenthesis ( ) operator tells the JavaScript execution engine to EXECUTE THE FUNCTION NOW.  PULL THE TRIGGER!  However, without the parenthesis, we're merely pointing to a function.  So, in that code, we're saying WHEN someone performs a click on the element called clickMe, THEN pull the trigger.  

If we put parenthesis on that line:

document.getElementById('clickMe').onclick = runTheExample();

... then we will fire the function right away.  That's not what we want.  We want to fire it off when the clickMe is clicked.

Does that help?