Top 10 Things that JavaScript Got Wrong!!!
reference from http://net.tutsplus.com/tutorials/javascript-ajax/top-10-things-that-javascript-got-wrong/

    JavaScript, if only by default, is one of the most popular programming languages available. Over the years, it's been labeled as a nightmare to work with, and, to some extent, this is true! However, more often than not, what people mean to say is that the DOM API is a nightmare. Nevertheless, there are a handful of flat-out errors in the language.

1. The Name. JavaScript is NOT Java

    We'll start with a fun jab at the name choice. While it was originally called Mocha, and then LiveScript, it was later changed to JavaScript. According to history, its similarities to the name Java was the result of a collaboration between Netscape and Sun, in exchange for Netscape bundling the Java runtime within their popular browser. It's also been noted that the name came, almost as a joke, due to the rivalry between LiveScript and Java for client-side scripting.

    Nevertheless, it resulted in thousands of "JavaScript has nothing to do with Java" comments in forums across the web!

2. Null is an Object?

    Consider this..

console.log(typeof null); // object 

.

    his makes zero sense. If null is the absence of a value, then how could its type be "object?" The simple answer is that it's flat-out an error that dates back to the first release of JavaScript - one that was even incorrectly carried over to Microsoft's JScript.

3. NaN !== NaN

    NaN, as we'd expect refers to a value that is not a legal number. The problem is that NaN isn't equal to anything...including itself.

   

  console.log(NaN === NaN); // false  

    This is just wrong. Instead, if you want to determine if a value is indeed NaN, you can use the isNaN() function.

4. Global Variables

    The dependence upon global variables is widely considered to be far and away the worst part of JavaScript. For simple projects, much like the quick tips on this site, it doesn't truly make a difference. However, the real burden of globals come into play when you begin referencing multiple scripts, without any knowledge of how they're created, or named. If they happen to share the same name as one of your variables, your program is going to throw some sort of error.

5. User-Agent Strings Report Mozilla. Ever Wonder Why?

    Alright - this one isn't the fault of JavaScript. I cheated a bit. It's because of the browser vendors. Having said that, user-agent string detection is very common in JavaScript; so it's important to know what you're dealing with. It probably doesn't belong in this list, but who cares! It's good to know.

    This one isn't as much a mistake as it was an unavoidable decision. For example, open Safari, access the Web Inspector, and log the user agent string into the console.

 
   console.log(navigator.userAgent);  
   // Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/531.21.8 (KHTML, like Gecko) Version/4.0.4 Safari/531.21.10  

    Note that first string of characters: Mozilla/5.0. Why would Safari identify it as a Mozilla based browser? Though it later correctly identifies itself, that still doesn't explain why they'd bother to mislead programmers. In fact, you'll find that most browsers identify themselves as Mozilla. The answer goes back a decade, and is, again, less an error, and more an unavoidable circumstance.

    For those unfamiliar, a user-agent string is simply me