announce knysa: write phantomjs scripts in "sync" style, i.e. without callbacks

[Bo Zou]

https://github.com/pahakia/knysa

download PDF from some web page can be done as follows:

kflow.knysa_open(url);
numPdfs = kflow.evaluate(function() {...});  // sandbox function
for (ix = 0; ix < numPdfs; ix++) {
   kflow.click(selector);
   kflow.sleep(5000); // sleep 5 seconds
   kflow.download(dir + '/' + filename_prefix + ix);
}

there is no callback!

[Bo Zou]

https://github.com/pahakia/knysa

compare knysa to casperjs:

casperjs script taken from http://docs.casperjs.org/en/latest/quickstart.html:

casper.start('http://google.fr/', function() {
    this.fill('form[action="/search"]', { q: 'casperjs' }, true);
});

casper.then(function() {
    links = this.evaluate(getLinks);
    this.fill('form[action="/search"]', { q: 'phantomjs' }, true);
});

casper.then(function() {
    links = links.concat(this.evaluate(getLinks));
});

knysa version:

kflow.knysa_open('http://google.fr/');
kflow.knysa_fill('form[action="/search"]', { q: 'casperjs' });
links = kflow.evaluate(getLinks);
kflow.knysa_fill('form[action="/search"]', { q: 'phantomjs' });
links = links.concat(kflow.evaluate(getLinks));

[Bo Zou]

https://www.infoq.com/articles/knysa-phantomjs-async-await

Intro to knysa: Async-Await Style PhantomJS Scripting

by Bo Zou on  Jul 21, 2016

Typical PhantomJS test frameworks suffer from callback hell and other tricks that reduce the clarity of how the program flows. Bo Zou created knysa which uses async-await style programming to eliminate these callbacks. Additionally, there's no need to resort to currying and common try-catch-fail constructs are used to maintain a sane path through the code.