Scratchpad is a convenient way to develop

and test your JavaScript. This website is

supposed to compare the two text areas

above and put the result underneath when

I clicked the "Diff" button. I've written

the HTML and CSS and included some

JavaScript library functions but I

haven't yet hooked them up so when I

click the button nothing happens.

Scratchpad is a source editor. When I click

display the code is evaluated in the

current page and the result is pasted

back into the pad as a comment. This is

telling me that I probably have a typo

in my selector.

Let's assign these two variables and

compare them using the library function.

DIsplay makes it really easy to check

that I'm on the right track.

Let's assign this to the output dev and this

time I'll choose run and it just runs the

script in the page. That looks good so

I'll wrap this in a function and assign

it the "Diff" button click event and this

time I'll choose reload and run.

It reloads the current page with the script

attached and "Diff" works. I can save this

file back to disk. Close Scratchpad.

Reload the page. This is just a really

quick introduction to Scratchpad.

For more information, visit developer.mozilla.org.