I have a colleague who uses Netbeans for Javascript so I took a look. And yes it looks better than the default Eclipse editor for Javascript (the jQuery auto-completion is quite interesting). But still it's not working in many situations, unlike the Java support that works all the time.
Yes of course you cannot accomplish exactly the same things with Javascript as with Java for the simple fact that Javascript is imposed as (almost) the only scripting language understood by the browser. To use Java on the client side (not as an applet) you need a generator like GWT or our own Strongly-typed Javascript (http://st-js.sourceforge.net ). I agree that the line of code is maybe not the best way to measure the cost of development but it's a simple way to compare similar languages (given that all the other costs of the project are the same regardless the language). Using multiple complex external and internal libraries, refactoring the code to adapt to new business requirements, debugging in Javascript seems very time consuming to me. The help of an IDE these days is extremely important. A simple syntax highlighter (even with some auto-complete support) is far from being enough. I'm still curious what IDE you used for your project and what was the cost, the size of a module where the requirements didn't change much. As a side question, how do you rename a method for example with the tool use (imagine that another method with the same name exists in a different class/module)?
We felt also the limits of Javascript especially for bigger projects. As we come from a Java background, we created the STJS project (Strongly-Typed Javascript : http://st-js.sourceforge.net). But as the author of the article, we felt that other frameworks doing similar job create a too big gap between the code in the source language and the generated code, so debugging directly in the browser becomes way too complicated. We want so far in our approach to stay as close as possible to Javascript that, for example, we forbid name of variables that are Javascript keywords, but not Java keywords (like var or prototype). What we needed was not to write less code (we don’t use Notepad – in Eclipse Ctrl+Space and a lot of code comes from IDE), but to have more help from modern IDE . We do believe in the importance of continually refactoring our code, eliminating dead code, controlling executions paths, things that seem to be unattainable by Javascript or some similar source languages translating to Javascript (Coffescript for example)