Replace all links in a string with <a> tags

output examples

Examples:
"Hello there google.com"  becomes   "Hello there <a href='http://google.com' target='_blank'>google.com</a>"
"Hello there http://google.com"  becomes   "Hello there <a href='http://google.com' target='_blank'>http://google.com</a>"
"Hello there http://google.com?q=test"  becomes   "Hello there <a href='http://google.com?q=test' target='_blank'>http://google.com?q=test</a>"

tests

/* =========================================================================
 * 
 *  get-links-from-string
 *      Tests getting links from a string
 *
 * ========================================================================= */
var _ = require('lodash');
var logger = require('bragi-browser');
var transformString = require('../../util/transform-string-with-links');

// util for tests
function getWrappedLink(original){
    var fqdn = original;
    if(!original.match(/^https?:\/\//)){ fqdn = 'http://' + original; }
    fqdn = fqdn.replace(/^(https?):\/\/\/\//, "$1://");
    return "<a href='" + fqdn + "' target='_blank'>" + original + "</a>";
}

// ====================================
//
// Tests
//
// ====================================
describe('Get Links from String', function (){
    describe('no links', function(){
        it('should not generate link for a bunch of strings', function(){
            _.each([
                'string', 'just a test message haha', 'simple test',
                'simple string hello world it\'s a little long'
            ], function(string){
                transformString(string).should.equal(string);
            });
        });
        it('should test periods', function(){
            _.each([
                'test.....test', 'test....test', 'test...test', 'test..test',
                '.com', '.net', '.x', '.xyzxyz', 'a..com'
            ], function(string){
                transformString(string).should.equal(string);
            });
        });
    });


    describe('link tests', function(){
        it('should test no http links', function(){
            transformString('google.com').should.equal("<a href='http://google.com' target='_blank'>google.com</a>");
            transformString('google.co').should.equal("<a href='http://google.co' target='_blank'>google.co</a>");
            transformString('google.net').should.equal("<a href='http://google.net' target='_blank'>google.net</a>");
            transformString('imgur.com').should.equal("<a href='http://imgur.com' target='_blank'>imgur.com</a>");
        });
        it('should test with ports', function(){
            transformString('imgur.com:80').should.equal("<a href='http://imgur.com:80' target='_blank'>imgur.com:80</a>");
            transformString('imgur.com:8080').should.equal("<a href='http://imgur.com:8080' target='_blank'>imgur.com:8080</a>");
            transformString('imgur.com:8080/').should.equal("<a href='http://imgur.com:8080/' target='_blank'>imgur.com:8080/</a>");
        });
        it('should test with commas', function(){
            var string = 'imgur.com/aVsTm60,QBizuWp,CEvBkMb,G0U1rGC';
            transformString(string).should.equal(getWrappedLink(string));
            string = 'http://imgur.com/aVsTm60,QBizuWp,CEvBkMb,G0U1rGC';
            transformString(string).should.equal(getWrappedLink(string));

            // ports
            string = 'imgur.com:80/aVsTm60,QBizuWp,CEvBkMb,G0U1rGC';
            transformString(string).should.equal(getWrappedLink(string));
            string = 'http://imgur.com:80/aVsTm60,QBizuWp,CEvBkMb,G0U1rGC';
            transformString(string).should.equal(getWrappedLink(string));
            string = 'http://imgur.com:1337/aVsTm60,QBizuWp,CEvBkMb,G0U1rGC';
            transformString(string).should.equal(getWrappedLink(string));
        });
        it('should add links for a bunch of links', function(){
            _.each([
                'http://www.reddit.com/r/fiveapp/comments/320wzu/live_chat_nils_is_da_bauf',
                'http://reddit.com', 
                'http://www.reddit.com/r/fiveapp/comments/320wzu/live_chat_nils_is_da_bauf/',
                'http://www.reddit.com/message/moderator/',
                'http://imgur.com/hzrGykL', 
                'http://www.reddit.com/r/pics/comments/320m7t/this_is_the_moment_i_knew_that_i_had_finally_made/',
                'http://www.reddit.com/r/pics/comments/320m7t/this_is_the_moment_i_knew_that_i_had_finally_made',
                'https://reddit.com',
            ], function( string ){
                transformString(string).should.equal(getWrappedLink(string));
            });
        });
        it('should test subdomains', function(){
            _.each([
                'http://www.reddit.com', 'http://www.test.reddit.com',
                'http://dev.test.reddit.com', 'http://inner.dev.test.reddit.com',
                'http://inner.inner.dev.test.reddit.com',
                'http://inner.inner.inner.dev.test.reddit.com',
                'http://reallylonginnersubdomainname.reddit.com',
                'http://inner.inner.inner.inner.dev.test.reddit.com',
                'http://inner.inner.inner.inner.inner.dev.test.reddit.com',
            ], function( string ){
                transformString(string).should.equal(getWrappedLink(string));
            });
        });
        it('should test ur with query', function(){
            _.each([
                'google.com?q=test', 'google.com?q=testgoogle.com?q=test',
                'google.com:8080?q=test', 'inner.google.com:8080?q=test',
                'inner.inner.google.com:8080?q=test',
                'innerreaaaaaaaaaaaaaaaaaaalylong.inner.google.com:8080?q=test',
                'innerreaaaaaaaaaaaaaaaaaaalylong.inner.google.com:8080?q=test/test',
                'http://google.com?q=test', 'http://google.com?q=test&z=24',
                'http://google.com?q=test&z=24,x=521'
            ], function( string ){
                transformString(string).should.equal(getWrappedLink(string));
            });
        });
        it('should test other formats of URLs', function(){
            _.each([
                '//i.imgur.com/Pu3I8av.png',
                '//cdnjs.cloudflare.com/test/libs/1140/2.0/1140.css',
            ], function(string){
                transformString(string).should.equal(getWrappedLink(string));
            });
        });
    });


    describe('should test MULTIPLE links in string', function(){
        it('should test multiple simple (non http) links in string', function(){
            transformString('google.com hey check it out test.com').should
                .equal(getWrappedLink('google.com') + ' hey check it out ' + getWrappedLink('test.com'));
            transformString('google.com reddit.com test.com').should
                .equal(getWrappedLink('google.com') + ' ' + 
                        getWrappedLink('reddit.com') + ' ' +
                        getWrappedLink('test.com'));
            transformString('google.comreddit.com test.com').should
                .equal(getWrappedLink('google.comreddit.com') + ' ' + 
                        getWrappedLink('test.com'));
            transformString('check it out reddit.com').should.equal('check it out ' +
                getWrappedLink('reddit.com'));
            transformString('pasting imgur.com/zwbZO,mn5C5HZ,LpeTpza will not break it')
                .should.equal('pasting ' + 
                    getWrappedLink('imgur.com/zwbZO,mn5C5HZ,LpeTpza') + 
                    ' will not break it');
        });

        it('should test multiple non simple links', function(){
            transformString('http://i.imgur.com/Pu3I8av.png - https://i.imgur.com/NA.png')
                .should.equal(
                    getWrappedLink('http://i.imgur.com/Pu3I8av.png') + ' - ' + getWrappedLink('https://i.imgur.com/NA.png'));
            transformString('i.imgur.com/Pu3I8av.png - https://i.imgur.com/NA.png')
                .should.equal(
                    getWrappedLink('i.imgur.com/Pu3I8av.png') + ' - ' + getWrappedLink('https://i.imgur.com/NA.png'));
            transformString('//i.imgur.com/Pu3I8av.png //i.imgur.com/NA.png')
                .should.equal(
                    getWrappedLink('//i.imgur.com/Pu3I8av.png') + ' ' + getWrappedLink('//i.imgur.com/NA.png'));
            transformString('//i.imgur.com/Pu3I8av.png some space //i.imgur.com/NA.png')
                .should.equal(
                    getWrappedLink('//i.imgur.com/Pu3I8av.png') + ' some space ' + getWrappedLink('//i.imgur.com/NA.png'));
        });

        it('should test a mixture of links', function(){
            transformString('//i.imgur.com/Pu3I8av.png - https://i.imgur.com/NA.png :: i.imgur.com/NA.png?test=42 https://i.imgur-test.com/NA.png')
                .should.equal(
                    getWrappedLink('//i.imgur.com/Pu3I8av.png') + ' - ' + 
                    getWrappedLink('https://i.imgur.com/NA.png') + ' :: ' +
                    getWrappedLink('i.imgur.com/NA.png?test=42') + ' ' +
                    getWrappedLink('https://i.imgur-test.com/NA.png')
                );
            // trailing space
            transformString('//i.imgur.com/Pu3I8av.png - https://i.imgur.com/NA.png :: i.imgur.com/NA.png?test=42 https://i.imgur-test.com/NA.png ')
                .should.equal(
                    getWrappedLink('//i.imgur.com/Pu3I8av.png') + ' - ' + 
                    getWrappedLink('https://i.imgur.com/NA.png') + ' :: ' +
                    getWrappedLink('i.imgur.com/NA.png?test=42') + ' ' +
                    getWrappedLink('https://i.imgur-test.com/NA.png') + ' '
                );
        });
    });
});

transformString

var _ = require('lodash');

// simple, but probably more prone to error
var LINK_REGEX = /(https?:\/\/|\/\/)?([^ .]+\.)+[^ .]+ /gi;

// more complex, but more explicit
var LINK_REGEX = /(https?:\/\/|\/\/)?([-a-zA-Z0-9@:%_\+~]+\.[a-z]{2,6}){1,100}((:[0-9]{1,6})?((\/|\?)?([-a-zA-Z0-9@:%_\+.,~#?&//=]*)?)?)? /gi;

function transformString( string ){
    string += ' '; // add trailing space (for regex)

    var urls = string.match(LINK_REGEX);
    
    if(urls){
        _.each(urls, function(originalUrlMatch){
            // LINK REPLACEMENT
            var replacementUrl = originalUrlMatch.replace(/ $/,'');

            // ensure there's some preceeding text
            if(!(replacementUrl.match(/^https?:\/\//))){
                replacementUrl = 'http://' + replacementUrl.replace(/^\/\//,''); 
            }

            string = string.replace(
                //new RegExp(originalUrlMatch), 
                originalUrlMatch, 

                "<a href='" + replacementUrl + "' target='_blank'>" +
                originalUrlMatch.replace(/ $/,'') + "</a> "
            );
        });
    }

    // remove trailing space
    string = string.substring(0, string.length-1);
    return string;
}

module.exports = transformString;