CODEWITHSUNDEEP
javascriptjqueryarrayscasperjs
user1257255
user1257255

Reputation: 1171

Correctly iterating through array and open pages with CasperJS

I'm working on a little project with CasperJS. The main idea is to get a links to pictures with title and description from subpages of some website. I already tried many different ways to achieve what I want, but I'm stuck with some piece of code and I don't want to continue with a possibly uncorrect way of coding.

This is current sequence of events in my code:

casper.start(url);
casper.thenEvaluate(openPicturesSubpage);
casper.then(getPicturesInfo);
casper.then(getPictureFullRes);
casper.run();

First two commands are working as expected, so I will skip to the structure of third function. The code of function (I'm using jQuery, because I need to get some specific stuff in other function) getPicturesInfo (variable pictures is global):

getPicturesInfo = function() {
  pictures = this.evaluate(function() {
    var array = [];
    $('.picture-box a').each(function() {
      arr.push({
        'name': $(this).text(),
        'subpage': $(this).attr('href')
      });
    });
    return array;
  });
}

Basically I have everything I need to continue "browsing" for actual full resolution links of pictures. So the next step is to append new data to already created array. This is also the main problem I want to solve. How to correctly iterate through array of previously saved data? So there's the code of the last function getPictureFullRes:

getPictureFullRes = function() {
  for (var i = 0; i < pictures.length; i++) {
    this.thenOpen(pictures[i]['subpage'], getFullResLink);
  }
}

The problem there is that I can't pass counter variable i to my function getFullResLink. I also tried to add another argument to thisOpen method and argument to getFullResLink function, but it doesn't work, because method don't have that functionality.

How could I access appropriate index of array inside getFullResLink?

Upvotes: 1

Views: 225

Answers (1)

Artjom B.
Artjom B.

Reputation: 61922

I see two possible ways to solve this.

Use a closure

Define a getFullResLinkWrapper like this:

function getFullResLinkWrapper(pictureIndex){
    return function(){
        // contents of getFullResLink that uses `pictureIndex`
    };
}

You can then call it like this:

this.thenOpen(pictures[i]['subpage'], getFullResLinkWrapper(i));

This way you can enclose the index variable for each iteration of getFullResLink.

Count inside of the function

It is guaranteed that then() steps are not skipped during the execution of CasperJS. So you can easily advance the counter inside of the getFullResLink function:

function getFullResLink(){
    if (pictureIndex == null) {
        pictureIndex = 0;
    } else {
        pictureIndex++;
    }
    ...
}

Upvotes: 2

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