摘自：https://plus.google.com/u/0/114723964985237592593/posts/Q5k16je1Siy

The relationship between JavaScript and the web resembles that of C and UNIX. Ubiquitous, but offering tempting opportunities to shoot yourself in the foot. Not since C have we had a language so universally available and (mis)understood, yet undeniably an important and enabling part of the web.

Here are some of the most important the ways JavaScript manifests.

Virtual machine — an increasing number of multimedia tools and programming languages compile down to JavaScript to execute in the browser. This means that you don't need to use JavaScript the language. (I'm a fan of ClojureScript.)

Network services — thanks to Node.js, JavaScript is a popular choice for network applications with a high number of parallel connections.

Framework substrate — due to its malleability, JavaScript has been the perfect substrate for sophisticated frameworks such as jQuery. JavaScript's origins in real computer science ideas have ensured it retained the respect of some serious engineers.

Entry-level language — it used to be kids got a start with BASIC. And in UNIX days, every machine was guaranteed a C compiler. Now JavaScript and HTML is the language that comes built into every computer.