CasperJS循环或遍历多个网页？

Question

我有一个CasperJS脚本，可以从一个网页上删除评级和日期。 现在我想从同一网站下的多个页面中抓取相同的数据。 如何在给定此代码的情况下遍历不同的子页面：

var ratings = [];
var dates = [];
var casper = require('casper').create({

    pageSettings: {
        loadImages:  false,         
        loadPlugins: false          
    },
    logLevel: "debug",             
    verbose: true                   
});

var fs = require('fs');

function getRatings() {
    var ratings = document.querySelectorAll('#BVRRRatingOverall_Review_Display > div.BVRRRatingNormalImage > img');
    return Array.prototype.map.call(ratings, function(e) {
        return e.getAttribute('title');
    });
}

function getDate() {
    var dates = document.querySelectorAll('#BVSubmissionPopupContainer > div.BVRRReviewDisplayStyle5Header > div.BVRRReviewDateContainer > span.BVRRValue.BVRRReviewDate');

    return Array.prototype.map.call(dates, function(e) {

        return e.innerHTML;

    });
}

casper.start('http://www.t-mobile.com/cell-phones/samsung-galaxy-s-5.html?bvrrp=9060/reviews/product/1/598aea53-16d0-4c12-b53a-105157092c52.htm', function(){

    this.echo('hi');
});

casper.then(function() {

    ratings = this.evaluate(getRatings);
    dates = this.evaluate(getDate);

    this.echo(ratings);
});


casper.run(function() {

    this.echo(ratings.length + ' ratings found:');

     for(var i=0; i<ratings.length; i++){
        ratings[i] = ratings[i]+': '+dates[i];
        dates[i] = '';
     }
    this.echo(ratings);
    var content = ratings;

    content = content.join("\n");

    fs.write("C:/Users/Karan/Copy/tweesis/implementation/scraping/samsungratings.txt", content, 'w'); 

    this.echo(dates.length + ' dates found:').exit();



});

任何帮助表示赞赏:)

Answer 1

由于存在下一页按钮，您可以使用它来递归遍历所有页面：

function getRatingsAndWrite(){
    ratings = casper.evaluate(getRatings);
    dates = casper.evaluate(getDate);

    casper.echo(ratings);
    casper.echo(ratings.length + ' ratings found:');

    for(var i=0; i<ratings.length; i++){
        ratings[i] = ratings[i]+': '+dates[i];
        dates[i] = '';
    }
    casper.echo(ratings);
    var content = ratings;

    content = content.join("\n");

    fs.write("C:/Users/Karan/Copy/tweesis/implementation/scraping/samsungratings.txt", content, 'a'); 

    casper.echo(dates.length + ' dates found:');

    var nextLink = ".BVRRPageLink.BVRRNextPage > a";
    if (casper.visible(nextLink)) {
        casper.thenClick(nextLink);
        casper.then(getRatingsAndWrite);
    } else {
        casper.echo("END")
    }
}

casper.start('http://www.t-mobile.com/cell-phones/samsung-galaxy-s-5.html?bvrrp=9060/reviews/product/1/598aea53-16d0-4c12-b53a-105157092c52.htm');

casper.then(getRatingsAndWrite);

casper.run();

一个相关的答案是A：CasperJS在点击按钮后解析下一页 。

Answer 2

这段代码可以帮助您：在一个对象数组中定义所需的URL，每个页面的选择器，并在循环中执行您想要对这些属性执行的操作。

您可以在循环中使用click方法而不是url。

var navigation = [
    {
        url: 'http://www.t-mobile.com/cell-phones/samsung-galaxy-s-5.html?bvrrp=9060/reviews/product/1/598aea53-16d0-4c12-b53a-105157092c52.htm', 
        selectorRatings:'#BVRRRatingOverall_Review_Display > div.BVRRRatingNormalImage > img', selectorDate :'#BVSubmissionPopupContainer > div.BVRRReviewDisplayStyle5Header > div.BVRRReviewDateContainer > span.BVRRValue.BVRRReviewDate'
    }
    ,{
        url: 'yourSecondUrl, etc...',
        selectorRatings:'#BVRRRatingOverall_Review_Display > div.BVRRRatingNormalImage > img',
        selectorDate :'#BVSubmissionPopupContainer > div.BVRRReviewDisplayStyle5Header > div.BVRRReviewDateContainer > span.BVRRValue.BVRRReviewDate'
    }
],
content = "";

    casper.start()
    .then(function(){
        //loop on the array
        navigation.forEach(function(navIndex){
            //open url : property url 
            casper.thenOpen(navIndex.url)
            //wait for the page to load -> must be useless because thenOpen() do it
            .waitForUrl(navIndex.url, function(){
                //get the value of attribute title of adequate selector
                var ratings = this.getElementAttribute(navIndex.selectorRatings, 'title'),
                //get the HTML of adequate selector
                var dates = this.getHTML(navIndex.selectorDates);
                this.echo(ratings);
                this.echo(dates);
                content = content +  ' ' + ratings + ' ' + dates;
            }); 
        });
    })
    .run(function() {
            this.echo('----------- All steps done ------------\n');
            this.exit();
    });

Answer 3

感谢Fanch和Artjom B.你的两个答案都提供了有效的解决方案。 我使用了Artjom B给出的分页上的“下一页”的递归遍历。接下来，我添加了一个wait（）函数，以确保在抓取它们之前加载下一个评级页面。 如果没有这个wait（）函数，我们会在点击'next'和resp之间多次刮同一页。 下一页完成加载。 请参阅下面的工作代码：

var ratings = [];
var dates = [];
var casper = require('casper').create({

    pageSettings: {
        loadImages:  false,         
        loadPlugins: false          
    },
    logLevel: "debug",               
    verbose: true                   
});

var fs = require('fs');

function getRatings() {
    var ratings = document.querySelectorAll('#BVRRRatingOverall_Review_Display > div.BVRRRatingNormalImage > img');
    return Array.prototype.map.call(ratings, function(e) {
        return e.getAttribute('title');
    });
}

function getDate() {
    var dates = document.querySelectorAll('#BVSubmissionPopupContainer > div.BVRRReviewDisplayStyle5Header > div.BVRRReviewDateContainer > span.BVRRValue.BVRRReviewDate');

    return Array.prototype.map.call(dates, function(e) {

        return e.innerHTML;

    });
}

function getRatingsAndWrite(){
    ratings = casper.evaluate(getRatings);
    dates = casper.evaluate(getDate);


    casper.echo(ratings.length + ' ratings found:');

     for(var i=0; i<ratings.length; i++){
        var rating = ratings[i].substr(0,1);
        ratings[i] = rating +': '+dates[i];
        dates[i] = '';
    } 

    var content = ratings;

    content = content.join("\n");

    fs.write("<filepath to write content>", content, 'a'); 

    casper.echo(dates.length + ' dates found:');

    var nextLink = ".BVRRPageLink.BVRRNextPage > a";
    if (casper.visible(nextLink)) {
        casper.thenClick(nextLink);
        casper.wait(3000);
        casper.then(getRatingsAndWrite);
    } else {
        casper.echo("END")
    }
}

casper.start('http://www.t-mobile.com/cell-phones/htc-one-m8.html');

casper.then(getRatingsAndWrite);

casper.run();