{"id":120,"date":"2011-02-21T17:14:27","date_gmt":"2011-02-22T00:14:27","guid":{"rendered":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/?p=120"},"modified":"2011-02-21T17:16:14","modified_gmt":"2011-02-22T00:16:14","slug":"javascript-and-nodejs","status":"publish","type":"post","link":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/javascript-and-nodejs\/","title":{"rendered":"Playing with JavaScript and node.js"},"content":{"rendered":"

I really enjoy learning new things in the field of computer science.\u00a0 Recently I have been learning some new computer languages and having a great time into the bargain.\u00a0 Ruby is my favourite, but I’ve also started playing with node.js which is an asynchronous IO library bundled with an implementation of JavaScript (or ECMAscript) because substack <\/a>has been Plurking about how wonderful it is.\u00a0 I’m not all that keen on JavaScript so far, partly because I’m so keen on Ruby and partly because of the criticism of it by Douglas Crockford<\/a> in his book JavaScript: The Good Parts<\/a>.\u00a0 However he is not totally anti-JavaScript and has spent a lot of time working on its standardisation as described in a YUI Theatre video called The State and Future of JavaScript<\/a>.\u00a0 (This was very interesting for me, for reasons some people may know, though of course I didn’t agree with everything he said.)\u00a0 There’s a bunch of intriguing talks available at The YUI Theater<\/a> which I’d love to watch.\u00a0 I did watch the one by Ryan Dahl on node.js<\/a> and I expect I will go back for more.<\/p>\n

The computer on my desk at home runs Windows (XP SP3 at the moment) rather than my beloved NetBSD or a Linux variant.\u00a0 Of course my servers run real OSes, but I wanted to work on my desktop machine and so spent a while installing node.js<\/a>, its package manager and associated packages under Cygwin<\/a>, which is what makes programming on a Windows machine bearable for me.\u00a0 The node.js installation instructions<\/a> cover Cygwin separately<\/a> and the instructions there worked for me.\u00a0 However I had a problem using the Node.js Package Manager<\/a> to install third-party modules.\u00a0 As described in this email thread<\/a>, Cygwin pipelines into gzip can hang in certain environments.\u00a0 I spent hours rebooting, reinstalling and futzing around until I found that thread, which goes on to lay the blame on a “BLODA<\/a>“.\u00a0 It turns out that certain antivirus applications can cause this, by hooking themselves into the system call invocation chain in a way which doesn’t actually work perfectly.\u00a0 I turned my AVG Antivirus Free (v11) off for 30 seconds during the installation of this particular package (called “request<\/a>“) and the installation went like a dream.<\/p>\n

Node.js is young software and under frenetic development.\u00a0 One promising use-case is the implementation of very scalable web applications, where the asynchronous IO model can yield great efficiencies.\u00a0 My interest in it is as a web client, where I hope to use it to retrieve and execute JavaScript from websites whose applications depend on it, but with which I want to interact with programatically rather than manually in a browser.\u00a0 Some such websites (for example Plurk<\/a>) provide proper APIs for this, whereas others, such as Facebook, do not.\u00a0 Facebook requires you to write a Facebook application instead.<\/p>\n

A consequence of node.js’s youth is the immaturity of adjunct libraries for interaction with other services.\u00a0 Although HTTP is treated as a first-class application with built-in support, that support is primitive at this stage when compared with Ruby’s net\/http<\/a>.\u00a0 I’ve been exploring the available libraries for node, which for HTTP client applications include node-httpclient<\/a>, node-get<\/a>, node-http-digest<\/a>, request<\/a> and abstract-http-request <\/a>of which the last two look particularly promising.\u00a0 None of them appear to offer cookie storage between requests, which is something I will need.\u00a0 At the moment I’m thinking of using one of the available key-value storage libraries which are available to store cookies.<\/p>\n

Once one receives the appropriate page from the server, the HTML may need parsing (and there are plenty of HTML parsers for node, such as this<\/a>), and scripts therein will need executing (aha! That’s why I’m using JavaScript to write the program!).\u00a0 That’s all in the future.\u00a0 For now, I’m able to run simple JavaScript programs which fetch pages from websites, and ready to start the real work.<\/p>\n","protected":false},"excerpt":{"rendered":"

I really enjoy learning new things in the field of computer science.\u00a0 Recently I have been learning some new computer languages and having a great time into the bargain.\u00a0 Ruby is my favourite, but I’ve also started playing with node.js which is an asynchronous IO library bundled with an implementation of JavaScript (or ECMAscript) because […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[18,19],"class_list":["post-120","post","type-post","status-publish","format-standard","hentry","category-technology","tag-javascript","tag-nodejs"],"_links":{"self":[{"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/posts\/120","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/comments?post=120"}],"version-history":[{"count":3,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/posts\/120\/revisions"}],"predecessor-version":[{"id":122,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/posts\/120\/revisions\/122"}],"wp:attachment":[{"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/media?parent=120"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/categories?post=120"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.lemongrass.org.uk\/lemongrass\/wp-json\/wp\/v2\/tags?post=120"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}