how do you develop long bookmarklets?

[Yoo]

To edit or modify a bookmarklet code, it must be in the form of a multi
line code in a html file or a js file.
But to test or run the bookmarklet, I need to do three things:
1. go to online bookmarklet builder site
2. paste my (multi-line) code there and generate bookmarklet link
3. drag it to toolbar
And I need to go thru these tedious three steps several times because
developing a long bookmarklet (like MyPage) is not like:
write code -test it -done.
but it's like:
write code -test it -it doesn't work. -modify code(put debugging
code) -test it -it still not work -modify code -...
How do you get around with this tediousness? Is there a way to skip the
three steps?

[VK]

Yoo wrote:

write code -test it -it doesn't work. -modify code(put debugging
code) -test it -it still not work -modify code -...
How do you get around with this tediousness? Is there a way to skip the
three steps?

Very easy.
When user chooses a bookmarklet from her favorites it is equivalent of
executing some JavaScript code withing the security settings of the
current page.

So simply develope and test some code in the regular way on your
computer:

<script type="text/javascript">
function futureBookmarklet() {
// the code you are making
}
window.onload = futureBookmarklet;
</script>

After you are done and all is working as expected place the body of the
function into the regular bookmarklet envelope (no escape needed):

javascript:void((function(){
// the code you are making
})())

make a link of it:

<a href="javascript:void((function(){
// the code you are making
})())">Bookmarklet name</a>

add bookmark to your favorites and test on pages in the Internet zone.
On this final step you check that:
1) you bookmarklet doesn't violate Internet zone sandbox
2) Its automatically escaped source doesn't exceed 2,083 characters URL
length limit imposed by IE
<http://support.microsoft.com/kb/208427>

After that you are done completely.