Why can I only evaluate an anonymous function in spookyjs (casperjs)

Question

I'm building a web scraper using spookyjs: https://github.com/WaterfallEngineering/SpookyJS

I created a new spooky object and I'm trying to evaluate a function that returns the contents of a certain html tag. For the sake of readability I'm trying to use a function (returnDataFromSelector()) to do this each time. However when I pass the function through evaluate it returns null.

When I use an anonymous function it works correctly. How can I get the returnDataFromSelector function work correctly?

   spooky.then(function() {
      function returnDataFromSelector(selector) {
        return function () {
          return document.querySelectorAll(selector)[0].innerHTML;
        }
      }
      var pageData = {};
      pageData.projectName = this.evaluate(returnDataFromSelector('a.green-dark')); // returns null
      pageData.projectName = this.evaluate(function () { return document.querySelectorAll('a.green-dark')[0].innerHTML;}); // returns correct string
      this.emit('pageData', pageData);
    });

Answer 1

The selector variable is not in the correct context. You should pass the selector separately into spooky.evaluate:

spooky.then(function() {
    function returnDataFromSelector(selector) {
        return document.querySelectorAll(selector)[0].innerHTML;
    }
    var pageData = {};
    pageData.projectName = this.evaluate(returnDataFromSelector, 'a.green-dark');
    pageData.projectName = this.evaluate(function () {
        return document.querySelectorAll('a.green-dark')[0].innerHTML;
    });
    this.emit('pageData', pageData);
});