Javascript on galvanist

macOS JavaScript for Automation (JXA) Notes

Sat, 28 Mar 2020 18:28:48 +0100

Overview

There is a macOS feature called the Open Scripting Architecture (OSA) which provides an infrastructure for intercommunication and automation of macOS software. One of the officially supported OSA languages is JavaScript and its use in this context is called “JavaScript for Automation” which is often abbreviated to “JXA”.

The idea is that instead of using AppleScript, you can program & automate macOS using a more modern language like JavaScript. This gives the programmer access to the enormous ecosystem of javascript libraries and tools in addition to all the modern optimizations and language features of ES6-ish JavaScript. JXA also provides access to a built-in Objective-C bridge that enables access to the file system and the ability to call into the Cocoa frameworks and plain C functions. JXA can basically do anything native code can. It’s a bit like node without needing to install node.

More Web Scraping with Phantomjs & CoffeeScript

Thu, 20 Mar 2014 03:33:00 +0000

I’ve been playing with Phantomjs and CoffeeScript a bit more. In this example I load the first page of google news, extract all the links and link text, and write them to stdout in markdown format.

# headlines: generate markdown-formatted output with just the headlines
# and links from the main google news page (no sections, nothing fancy)
page_url = 'http://news.google.com/'
jquery_url = 'http://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js'
page = require("webpage").create()
	
# this is a handler that relays console messages from inside our page to
# the phantomjs console. I've made it ignore everything that isn't
# prefixed with the word 'headline:'
page.onConsoleMessage = (msg) ->
    if msg.substring(0, 9) is "headline:"
        console.log(" - " + msg.substring(9))
	
	
page.open page_url, (status) ->
    if status isnt "success"
        console.log "# Error: couldn't load the page"
        phantom.exit()
    console.log "# The News\n"
    page.includeJs jquery_url, ->
        page.evaluate ->
            $('a.article').has('span.titletext').each (indx, elem) ->
                title = $(elem).text()
                href = $(elem).attr 'href'
                console.log "headline:[#{title}](#{href})"
        phantom.exit()  # I need this here to let the evaluate finish

Getting to know CoffeeScript

The combination of CoffeeScript an jQuery feels natural. But the overall program feels pretty brittle, and the phantomjs error messages that were printed while I was writing this little script weren’t very helpful. To be fair, part of this relates to CoffeeScript. I’m still getting used to it, and I’m in the phase where overlooked unbalanced parens or unintentionally ambiguous expressions cost me lots of time to debug.

Javascript Duration Seconds to Years, Days, Hours, Minutes, Seconds

Thu, 06 Mar 2014 06:24:00 +0000

For a recent project I needed to express the difference between date objects as a string. Here’s an algorightm I’ve been using for a while. This time in JavaScript. JavaScript isn’t my best language, so if you have any suggestions for improvement, please let me know.

function fmt_duration(seconds, detail) {
  // Return a string containing the number of years, days, hours,
  // minutes, and seconds in the given numeric seconds argument.
  // The optional detail argument can limit the about of detail.
  // Note: 1 year is treated as 365.25 days to approximate "leap
  // years" TAGS: secToYMDHMS, secToDHMS
  //
  // Some Examples:
  // 
  // fmt_duration(35000000)
  // returns "1 year, 39 days, 20 hours, 13 minutes, 20 seconds"
  //
  // fmt_duration(24825601)
  // returns "287 days, 8 hours, 1 second"
  //
  // fmt_duration(24825601, 3)
  // returns "287 days, 8 hours"
  //
  // fmt_duration(24825601, 1)
  // returns "less than one year"
  // 
  "use strict";
  var labels = ['years', 'days', 'hours', 'minutes', 'seconds'],
    increments = [31557600, 86400, 3600, 60, 1],
    result = "",
    i,
    increment,
    label,
    quantity;
  detail = detail === undefined ? increments.length : detail;
  detail = Math.min(detail, increments.length);
	
  for (i = 0; i < detail; i += 1) {
    increment = increments[i];
    label = labels[i];
	
    if (seconds >= increment) {
      quantity = Math.floor(seconds / increment);
      if (quantity === 1) {
        // if singular, strip the 's' off the end of the label
        label = label.slice(0, -1);
      }
      seconds -= quantity * increment;
      result = result + " " + quantity + " " + label + ",";
    }
  }
	
  result = result.slice(1, -1);
  if (result === "") {
    result = "less than one " + labels[detail - 1].slice(0, -1);
  }
	
  return result;
}

Javascript Date from Python datetime string representation

Thu, 06 Mar 2014 06:17:00 +0000

In a recent project I needed to convert the string representation of a Python datetime.datetime into a Javascript Date object. Here’s what I came up with. JavaScript isn’t my best language so if you have any suggestions for improvement, please let me know.

function datetimeToDate(datetime_str, use_utc) {
  // Return a JS Date object from the given python datetime_str string.
  // if the optional boolean use_utc argument is given, the datetime_str
  // will be treated as a UTC datetime_str
  "use strict";
  var datetime_parts = datetime_str.split(" ", 2),
    date_parts = datetime_parts[0].split("-"),
    time_parts = datetime_parts[1].split(":"),
    second_parts = time_parts[2].split('.'),
    mkdate,
    s2i,
    smu2ims;
  use_utc = use_utc === undefined ? false : use_utc;
	
  // The Date constructors don't work with .apply(), so lambdas
  if (use_utc) {
    mkdate = function (y, m, d, hr, min, sec, ms) {
      return new Date(Date.UTC(y, m, d, hr, min, sec, ms));
    };
  } else {
    mkdate = function (y, m, d, hr, min, sec, ms) {
      return new Date(y, m, d, hr, min, sec, ms);
    };
  }
	
  // string to int with radix 10
  s2i = function (i_str) { return parseInt(i_str, 10); };
	
  // string microsecond (aka mu) to int millisecond (aka ms)
  smu2ims = function (f_str) {
    return Math.round(parseFloat(f_str) * 1000);
  };
	
  return mkdate(s2i(date_parts[0]), // year
                s2i(date_parts[1]) - 1, // month 
                s2i(date_parts[2]), // day
                s2i(time_parts[0]), // hour
                s2i(time_parts[1]), // minute
                s2i(second_parts[0]), // second
                smu2ims("." + second_parts[1])); // millisecond
}

Automating Unity

Thu, 22 Sep 2011 07:00:00 +0000

2011-09-22 : Amundsen-Scott South Pole Station

So we upgraded from what could generously be described as ancient versions of Cisco Unity (and CallManager) to much more modern versions. Sadly my hopes for a more featured and streamlined UI on these apps were dashed. Version 8.x is nearly identical in appearance to 4.x. One change I did notice was that the Unity web interface migrated from a form-based login to an only-slightly-better HTTP basic authentication login scheme. Anyway, in both the old and “new” versions it takes about 100 clicks to get to anything, so one of the first things I wanted to do when I got here was to automate my common Unity administration tasks.