Javascript 尝试使用casperjs遍历某些链接

Javascript 尝试使用casperjs遍历某些链接,javascript,web-scraping,casperjs,Javascript,Web Scraping,Casperjs,这就是我目前拥有的: var casper = require('casper').create(); var fs = require('fs'); var folderName = 'CARD_DATA'; var fileName = 'allChampionDecks.txt'; var save = fs.pathJoin(fs.workingDirectory, folderName, fileName); // init jquery var casper = require

这就是我目前拥有的:

var casper = require('casper').create();

var fs = require('fs');
var folderName = 'CARD_DATA';
var fileName = 'allChampionDecks.txt';
var save = fs.pathJoin(fs.workingDirectory, folderName, fileName);

// init jquery 
var casper = require('casper').create({
    clientScripts: ['jquery.min.js']
});

casper.start(URL, function() {

});

var links = ["http://magic.wizards.com/en/events/coverage/mtgochamp14","http://magic.wizards.com/node/335986","http://magic.wizards.com/en/events/coverage/2014WC"];
var i = -1;
var linkData = '';

// iterate
casper.then(function() {
    this.each(links, function() { 
        i++;
        this.thenOpen((links[i]), function() {
            linkData += this.evaluate(getLinkDeckData);
        });
    });

    fs.write(save, linkData + '\n', 'w');
});

// scrape
function getLinkDeckData() {
    var meta = $('.deck-meta h4');
    var event = $('.deck-meta h5');
    var allDecks = $('.toggle-text .deck-list-text');
    var json = '{';

    for(var i = 0; i < meta.length; i++) {
        json += '"event": "'+$(event[i]).text().trim()+'",'
            +'"deckName": "'+$(meta[i]).text()+'",'
            +'"deck": [';

        var cardCount = $(allDecks[i]).find('.sorted-by-overview-container .row .card-count');
        var cardName = $(allDecks[i]).find('.sorted-by-overview-container .row .card-name');

        for(var j = 0; j < cardCount.length; j++) {
            if(j < cardCount.length-1) 
                json += '{"quantity":"'+$(cardCount[j]).text()+'", "name":"'+$(cardName[j]).text()+'"},';
            else
                json += '{"quantity":"'+$(cardCount[j]).text()+'", "name":"'+$(cardName[j]).text()+'"}';
        }

        json += '],'
            +'"sideboard": [';

        var cardCount = $(allDecks[i]).find('.sorted-by-sideboard-container .row .card-count');
        var cardName = $(allDecks[i]).find('.sorted-by-sideboard-container .row .card-name');

        for(var j = 0; j < cardCount.length; j++) {
            if(j < cardCount.length-1) 
                json += '{"quantity":"'+$(cardCount[j]).text()+'", "name":"'+$(cardName[j]).text()+'"},';
            else
                json += '{"quantity":"'+$(cardCount[j]).text()+'", "name":"'+$(cardName[j]).text()+'"}';
        }

        if(i < meta.length-1) 
            json += '],'
        else
            json += ']}'
        /**/
    }

    return json;
}

casper.run();
所有
then*
(和
wait*
)函数都是异步步进函数。当您进行循环并在循环内调用
casper.thenOpen()
时,您将安排一个开始步骤,并附带一个
然后
回调作为单独的步骤

问题是,当您尝试编写
linkData
时,它不在单独的步骤中。只需将其包装在
casper.then()
中即可

固定片段:

casper.then(function() {
    links.forEach(links, function(link, i) { 
        this.thenOpen(link, function() {
            linkData += this.evaluate(getLinkDeckData);
        });
    });

    this.then(function(){
        fs.write(save, linkData + '\n', 'w');
    });
});

您应该使用
Array.prototype.forEach
,而不是使用CasperJS'
each
。这样,您就不需要全局计数器变量。

我对循环有一个问题,它是
then()
thenEvaluate()
在循环中不起作用:
casper.then(function() {
    links.forEach(links, function(link, i) { 
        this.thenOpen(link, function() {
            linkData += this.evaluate(getLinkDeckData);
        });
    });

    this.then(function(){
        fs.write(save, linkData + '\n', 'w');
    });
});