How do I get the absolute path for '<img src=''>' in node from the a response.body

问题

So I want to use request-promise to pull the body of a page. Once I have the page I want to collect all the tags and get an array of src's of those images. Assume the src attributes on a page have both relative and absolute paths. I want an array of absolute paths for imgs on a page. I know I can use some string manipulation and the npm path to build the absolute path but I wanted to find a better way of doing it.

var rp = require('request-promise'),
    cheerio = require('cheerio');

var options = {
    uri: 'http://www.google.com',
    method: 'GET',
    resolveWithFullResponse: true
};

rp(options)
  .then (function (response) {
    $ = cheerio.load(response.body);
    var relativeLinks = $("img");
    relativeLinks.each( function() {
        var link = $(this).attr('src');
        console.log(link);
        if (link.startsWith('http')){
            console.log('abs');
        }
        else {
            console.log('rel');
        }
   });
});

results

  /logos/doodles/2016/phoebe-snetsingers-85th-birthday-5179281716019200-hp.gif
  rel

回答1:

To get an array of image links in your scenario, you can use url.resolve to resolve relative src attributes of img tags with the request URL, resulting in an absolute URL. The array is passed to the final then; you can do other things with the array other than console.log if so desired.

var rp = require('request-promise'),
    cheerio = require('cheerio'),
    url = require('url'),
    base = 'http://www.google.com';

var options = {
    uri: base,
    method: 'GET',
    resolveWithFullResponse: true
};

rp(options)
    .then (function (response) {
        var $ = cheerio.load(response.body);

        return $('img').map(function () {
            return url.resolve(base, $(this).attr('src'));
        }).toArray();
    })
    .then(console.log);

This url.resolve will work for absolute or relative URLs (it resolves and returns the combined absolute URL when resolving from your request URL to a relative path, but when resolving from your request URL to an absolute URL it just returns the absolute URL). For example, with img tags on google with /logos/cat.gif and https://test.com/dog.gif as the src attributes, this would output:

[ 
    'http://www.google.com/logos/cat.gif',
    'https://test.com/dog.gif'
]

回答2:

Store your page URL as a variable use url.resolve to join the pieces together. In the Node REPL this works for both relative and absolute paths (hence the "resolving"):

$:~/Projects/test$ node
> var base = "https://www.google.com";
undefined
> var imageSrc = "/logos/doodles/2016/phoebe-snetsingers-85th-birthday-5179281716019200-hp.gif";
undefined
> var url = require('url');
undefined
> url.resolve(base, imageSrc);
'https://www.google.com/logos/doodles/2016/phoebe-snetsingers-85th-birthday-5179281716019200-hp.gif'
> imageSrc = base + imageSrc;
'https://www.google.com/logos/doodles/2016/phoebe-snetsingers-85th-birthday-5179281716019200-hp.gif'
> url.resolve(base, imageSrc);
'https://www.google.com/logos/doodles/2016/phoebe-snetsingers-85th-birthday-5179281716019200-hp.gif'

Your code would change to something like:

var rp = require('request-promise'),
    cheerio = require('cheerio'),
    url = require('url'),
    base = 'http://www.google.com';

var options = {
    uri: base,
    method: 'GET',
    resolveWithFullResponse: true
};

rp(options)
  .then (function (response) {
    $ = cheerio.load(response.body);
    var relativeLinks = $("img");
    relativeLinks.each( function() {
        var link = $(this).attr('src');
        var fullImagePath = url.resolve(base, link); // should be absolute 
        console.log(link);
        if (link.startsWith('http')){
            console.log('abs');
        }
        else {
            console.log('rel');
        }
   });
});

回答3:

It looks like you're using jQuery, so you could

$('img').each(function(i, e) {
    console.log(e.src)
});

If you use src it will expand relative paths to absolute ones.

来源：https://stackoverflow.com/questions/37733871/how-do-i-get-the-absolute-path-for-img-src-in-node-from-the-a-response-bo