Develop Reference

Removing elements of string before a specific repeated character in it in javascript

I'm trying to remove from my string all elements before an specific character which is repeated several times in this way:
let string = http://localhost:5000/contact-support
thus I´m just trying to remove everything before the third /
having as result:contact_support
for that i just set:
string.substring(string.indexOf('/') + 3);
Bust guess thats not the correct way
Any help about how to improve this in the simplest way please?
Thanks in advance!!!

It seems like you want to do some URL parsing here. JS brings the handful URL utility which can help you with this, and other similar tasks.
const myString = 'http://localhost:5000/contact-support';
const pathname = new URL(myString).pathname;
console.log(pathname); // outputs: /contact-support
// then you can also remove the first "/" character with `substring`
const whatIActuallyNeed = pathname.substring(1, pathname.length);
console.log(whatIActuallyNeed); // outputs: contact-support

Hope This will work
string.split("/")[3]
It will return the sub-string after the 3rd forward slash.

You could also use lastIndexOf('/'), like this:
string.substring(string.lastIndexOf('/') + 1);
Another possibility is regular expressions:
string.match(/[^\/]*\/\/[^\/]*\/(.*)/)[1];
Note that you must escape the slash, since it is the delimiter in regular expressions.

string.substring(string.lastIndexOf('/')+1) will also do the job if you are looking to use indexOf function explicitly.

How to get youku video id from url by regex?

I need to get youku video id from url by regex, for example:
http://v.youku.com/v_show/id_XNTg3OTc3MzY4.html
I only need XNTg3OTc3MzY4 to keep in a variable.
How can I write it in function below
var youkuEmbed = "[[*supplier-video]]";
var youkuUrl = youkuEmbed.match(/http://v\.youku\.com/v_show/id_(\w+)\.html/);
I tried this but it didn't work.
Thanks!

You can use a simple regex like this:
id_(\w+)
Working demo
The idea is to match the _id and the capture all the alphanumeric strings.
MATCH 1
1. [29-42] `XNTg3OTc3MzY4`
If you go the Code Generator section you can get the code. However, you can use something like this:
var myString = 'http://v.youku.com/v_show/id_XNTg3OTc3MzY4.html';
var myRegexp = /id_(\w+)/;
var match = myRegexp.exec(myString);
alert(match[1]);
//Shows: XNTg3OTc3MzY4

You can use this regex:
http://v\.youku\.com/v_show/id_(\w+)\.html
Your match is in the first capturing group.
Here is a regex demo.

Id the id always follows id_, you could possibly split the string.
'http://v.youku.com/v_show/id_XNTg3OTc3MzY4.html'.split(/.*id_|\./)[1]
//=> 'XNTg3OTc3MzY4'
For this specific string, you could just do.
'http://youku.com/id_XNTg30Tc3MzY4.html'.split(/id_|\./)[2]
//=> 'XNTg3OTc3MzY4'

It looks like you need to escape all the slashes because that's the delimiter for the regex itself:
var youkuUrl = youkuEmbed.match(/http:\/\/v\.youku\.com\/v_show\/id_(\w+)\.html/);
Then use the first capture group, as Unihedron stated.

Is it possible to cut off the beginning of a string using regex?

I have a string which contains a path, such as
/foo/bar/baz/hello/world/bla.html
Now, I'd like to get everything from the second-last /, i.e. the result shall be
/world/bla.html
Is this possible using a regex? If so, how?
My current solution is to split the string into an array, and join its last two members again, but I'm sure that there is a better solution than this.

For example:
> '/foo/bar/baz/hello/world/bla.html'.replace(/.*(\/.*\/.*)/, "$1")
/world/bla.html

You can also do
str.split(/(?=\/)/g).slice(-2).join('')

> '/foo/bar/baz/hello/world/bla.html'.match(/(?:\/[^/]+){2}$/)[0]
"/world/bla.html"
Without regular expression:
> var s = '/foo/bar/baz/hello/world/bla.html';
> s.substr(s.lastIndexOf('/', s.lastIndexOf('/')-1))
"/world/bla.html"

I think this will work:
var str = "/foo/bar/baz/hello/world/bla.html";
alert( str.replace( /^.*?(\/[^/]*(?:\/[^/]*)?)$/, "$1") );
This will allow for there being possibly only one last part (like, "foo/bar").

You can use /(\/[^\/]*){2}$/ which selects a slash and some content twice followed by the end of the string.
See this regexplained.

Match URL's which do NOT have a specific prefix

i match image urls inside a string with the following regular expression in javascript:
/\b(https?|ftp|file):\/\/[\-A-Z0-9+&##\/%?=~_|!:,.;]*[\-A-Z0-9+&##\/%=~_|]?(\.(jpe?g|png|gif))/ig
with the String.replace function, i wrap all matches inside an -tag.
in a second step i'd like to match all urls, which do not have the above file extensions as prefix. my first intention was to use the ?!-operator like this:
/\b(https?|ftp|file):\/\/[\-A-Z0-9+&##\/%?=~_|!:,.;]*[\-A-Z0-9+&##\/%=~_|]?(?!\.(jpe?g|png|gif))/ig
unfortunatly, this does no work. tried different variations of this expression, but with now results.
thanks for any help in advance,
manuel

Since you're asking about javascript, I think something like this could help :
var url_re = "\\b(https?|ftp|file):\\/\\/[\\-A-Z0-9+&##\\/%?=~_|!:,.;]*[\\-A-Z0-9+&##\\/%=~_|]?"
var re = new RegExp( "^(?!.*"+url_re+"\.(jpe?g|png|gif)).*"+url_re+"\.[a-z0-9_]+" , 'gi' )

Simple javascript regex

I need: www.mydomain.com:1235 form the text var below:
var text = 'http://www.mydomain.com:1235/;image.jpg';
alert(text.match(/\/[^]+\//));
output is: //www.mydomain.com:1235/
How do I exclude the delimiters?

You need to use parens to group what you want to match. Then, the call to .match() will let you use indexers. Index 0 is the whole string match, and index 1 is the first paren grouping.
var text = 'http://www.mydomain.com:1235/;image.jpg';
alert(text.match(/\/([^\/]+)\//)[1]);

Not a regex, but you could do this:
Example: http://jsfiddle.net/nTmv9/
text = text.split('http://')[1].split('/')[0];
or with a regex:
Example: http://jsfiddle.net/nTmv9/1/
text = text.match(/http:\/\/([^\/]+)\//)[1];

This will capture the domain without the http or the url slugs.
https?:\/\/([^\/]+)\/
If you need help figuring out regex here is a great tool I use all of the time.
http://gskinner.com/RegExr/
Cheers