URI.withinString - TypeError: Cannot read property 'length' of undefined

[dandreit]

Hi,

I'm using URI.js in node.js (v4.2.6) [ npm install --save urijs ]

And I wanted to extract several URLs from a text, so I wrote this little file:
lib/parseUrlsFromText.js:

const URI = require('urijs');

module.exports = function parseUrlsFromText(text) {
  console.log('text: ' + JSON.stringify(text, null, 2));
  var urls = [];
  URI.withinString(text, function(url) {
    console.log('detected url: ' + url);
    urls.push(url);
  });
  console.log('urls: ' + JSON.stringify(urls, null, 2));
  return urls;
};

* I then tried to test it, and then added the console.logs because of fails:
test/parseUrlsFromText.js:

const expect = require('chai').expect;
const parseUrlsFromText = require('../lib/parseUrlsFromText');

describe('lib/parseUrlsFromText.js', () => {

  // text: null
  // urls: []
  // -> OK
  it('should return empty array on \'null\' text', done => {
    expect(parseUrlsFromText(null)).to.deep.equal([]);
    done();
  });

  // text: "www.example.com"
  // detected_url: www.example.com
  // urls: []
  // result: 
  // -> TypeError: Cannot read property 'length' of undefined
  //    at Function.URI.withinString (node_modules/urijs/src/URI.js:972:40)
  it('should return a URL contained in \'www.example.com\'', done => {
    // expect(parseUrlsFromText('I love www.example.com!')).to.deep.equal(['example.com']);
    console.log('result: ' + parseUrlsFromText('www.example.com'));
    done();
  });

  // text: "I love example.com!"
  // urls: []
  // result:
  // -> Result empty, but NO BUG
  it('should return a URL contained in \'I love example.com!\'', done => {
    // expect(parseUrlsFromText('I love example.com!')).to.deep.equal(['example.com']);
    console.log('result: ' + parseUrlsFromText('I love example.com!'));
    done();
  });
...

I have not dug further, but this solved my problem:
In (node_modules/urijs/src/)URI.js:969 & 972
-> conditional add of slice.length and result.length

URI.withinString = function(string, callback, options) {
...
    while (true) {
      ...
      end = start + (slice && slice.length) ? slice.length : 0;
      var result = callback(slice, start, end, string);
      string = string.slice(0, start) + result + string.slice(end);
      _start.lastIndex = start + (result && result.length) ? result.length : 0;
    }

It may not be enough to make a Pull Request, but it's probably worth considering.
Hope that helps!
Cheers

[rodneyrehm]

Nice catch!

.withinString() expects the callback to return a string, which your code (parseUrlsFromText.js) does not do. Because of that result.length fails.

A fix, if you want to send a PR, would be to skip the string mutation and set _start.lastIndex = end in case result === undefined. Adding a test for non-mutating callbacks would round things off nicely. Please make sure to open the PR against master, not gh-pages.

[dandreit]

Thanks for your quick answer and clues!
I'll take a look and try to make it nicely. ; )

[dandreit]

Note to anyone experiencing the same problem:
Until something may be done to make .withinString usable as I tryed,
as mentioned by @rodneyrehm, simply return the text argument you passed.
My adapted example:
lib/parseUrlsFromText.js:

const URI = require('urijs');

module.exports = function parseUrlsFromText(text) {
  var urls = [];
  URI.withinString(text, function(url) {
    urls.push(url);
    return text;
  });
  return urls;
};

=> Closing the Issue, as it solves the problem