Develop Reference

Using Variable in Regex Character Set

i'm trying to use a variable (save) as a regex character set but keep getting null
function mutation(arr) {
var save = arr[1];
var rgx = /[save]/gi;
return arr[0].match(rgx).join('') == arr[0];
}
mutation(["Mary", "Army"]);
Goal of the function is to see if all the letters of arr[1] are contained in arr[0] by returning true or false. Function does work as i want it to when i manually put arr[1] into the character set (returns true in this situation), just cant get it to work with the variable.

Your exact current approach won't work (I think) due to it not being possible to build a regex pattern using /.../ notation with a variable. But, we can still use RegExp to build the pattern. For the sample data you showed us, here is a regex pattern which would work:
^(?!.*[^Mary]).*$`
In other words, we can assert, on the second string Army, that all its characters can be found in the first string Mary.
function mutation(arr) {
var save = arr[1];
var rgx = "^(?!.*[^" + save + "]).*$";
var re = new RegExp(rgx, "gi");
return re.test(arr[0]);
}
console.log(mutation(["Mary", "Army"]));
console.log(mutation(["Jon Skeet", "Tim Biegeleisen"]));

How get domain from string?

var string = "https://example.com/app/something";
var string = "example.com/app/something";
new URL(string.origin)
If string have protocol all ok, and if not. have error Failed to construct 'URL': Invalid URL(…)
How can I obtain the root domain without using regex?

The question is still a bit unclear, and I'm not entirely sure how you're getting that string, but just for the sake of argument, here's a quick solution:
function getHostname(str)
{
str = (/^\w+:\/\//.test(str) ? "" : "http://") + str
return new URL(str).hostname;
}
console.log(getHostname("https://example.com/app/something"));
console.log(getHostname("example.com/app/something"));
Yes, technically, this technically does use a regular expression to check if the protocol is present, but it uses the URL class actually parse the host name.

Regex example:
var example1 = "www.example1.com/test/path";
var example2 = "https://example2.com/test/path";
var example3 = "http://subdomain.example3.com/test/path";
function getDomain(str) {
var matches = str.match(/^(?:https?:\/\/)?((?:[-A-Za-z0-9]+\.)+[A-Za-z]{2,6})/);
if (!matches || matches.length < 2) return '';
return matches[1];
}
console.log(getDomain(example1));
console.log(getDomain(example2));
console.log(getDomain(example3));
References:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match
http://regexr.com/

If I understand your question correctly, you want to check if the URL contains either the http or https protocol. This can easily be done with string functions built into JavaScript as shown below.
var string = window.location;
if (string.includes('http') || string.includes('https'))
{
//Do your logic here
}
UPDATE: Alternatively, you could use substring functionality shown below.
var string = window.location;
if (string.indexOf('http') == 0)
{
//Do your logic here
}
Note that this will also verify that the http is at the beginning of the string and not just thrown in willy nilly.

How can we split a string using starts with regular expression (/^myString/g)

I am having a case where i need to split given string using starts with regex (/^'searchString'/) which is not working such as
"token=123412acascasdaASDFADS".split('token=')
Here i want to extract the token value but as there might be some other possible parameters such as
"reset_token=SDFDFdsf12313ADADF".split('token=')
Here it also split the string with 'token=', Thats why i need to split the string using some regex which states that split the string where it starts with given string.
Thanks..
EDITED
Guys thanks for your valuable response this issue can be resolve using /\btoken=/ BUT BUT its does not work if 'token=' stored as a string into a variable such as
sParam = 'token=';
"token=123412acascasdaASDFADS".split(/\bsParam/);
This does not works.

You can use regex in split with word boundary:
"token=123412acascasdaASDFADS".split(/\btoken=/)
If token is stored in a variable then use RegExp constructor:
var sParam = "token";
var re = new RegExp("\\b" + sParam + "=");
Then use it:
var tokens = "token=123412acascasdaASDFADS".split( re );

This is the use case for the \b anchor:
\btoken=
It ensures there's no other word character before token (a word character being [a-zA-Z0-9_])

You need to split the string using the & parameter delimiter, then loop through those parameters:
var token;
$.each(params.split('&'), function() {
var parval = this.split('=');
if (parval[0] == "token") {
token = parval[1];
return false; // end the $.each loop
}
});
if you just use token= as the split delimiter, you'll include all the other parameters after it in the value.

It's not clear what you need, but this may be an idea to work with?
var reqstr = "token=12345&reset_token=SDFDFdsf12313ADADF&someval=foo"
.split(/[&=]/)
,req = [];
reqstr.map( function (v, i) {
if (i%2==0) {
var o = {};
o[/token/i.test(v) ? 'token' : v] = reqstr[i+1];
this.push(o);
} return v
}, req);
/* => req now contains:
[ { token: '12345' },
{ token: 'SDFDFdsf12313ADADF' },
{ someval: 'foo' } ]
*/

You can try with String#match() function and get the matched group from index 1
sample code
var re = /^token=(.*)$/;
var str = 'token=123412acascasdaASDFADS';
console.log('token=123412acascasdaASDFADS'.match('/^token=(.*)$/')[1]);
output:
123412acascasdaASDFADS
If token is dynamic then use RegExp
var token='token=';
var re = new RegExp("^"+token+"(.*)$");
var str = 'token=123412acascasdaASDFADS';
console.log(str.match(re)[1]);
Learn more...

How do I extract data from this URL using javascript?

I need to build a string from the data contained in this url using javascript/jQuery:
http://www.example.com/members/admin/projects/?projectid=41
The string returned should look as follows:
/ajax/projects.php?projectid=41
Obviously if there is no query string present, the method should still return a string of the same format minus the query string. e.g.
http://www.example.com/members/admin/messages/
should return...
/ajax/messages.php
I've made numerous attempts, all met without success due to my poor grasp of regular expressions, and it feels as though the ore I rad on the subject the more I am confusing myself.
If someone could help it would be greatly appreciated.
EDIT: The 'admin' portion of the url is a users 'username' and could be anything.

Here's a function that will take your URL and return a new one according to the rules you've listed above:
function processURL(url) {
var base = "", query = "";
var matches = url.match(/([^\/\?]+)(\/$|$|\?|\/\?)/);
if (matches) {
base = matches[1];
matches = url.match(/\?[^\?]+$/);
if (matches) {
query = matches[0];
}
}
return("/ajax/" + base + ".php" + query);
}
And, a test app that shows it working on a bunch of URLs: http://jsfiddle.net/jfriend00/UbDfn/
Input URLs:
var urls = [
"http://www.example.com/members/admin/projects/?projectid=41",
"http://www.example.com/members/bob/messages/",
"http://www.example.com/members/jill/projects/",
"http://www.example.com/members/alice/projects?testid=99",
"http://www.example.com/members/admin/projects/?testid=99"
];
Output results:
/ajax/projects.php?projectid=41
/ajax/messages.php
/ajax/projects.php
/ajax/projects.php?testid=99
/ajax/projects.php?testid=99
To explain, the first regular expression looks for:
a slash
followed by one or more characters that is not a slash and not a question mark
followed by one of the four sequences
/$ a slash at the end of the string
$ end of the string
? a question mark
/? a slash followed by a question mark
The point of this regex is to get the last segment of the path that comes before either the end of the string or the query parameters and it's tolerant of whether the last trailing slash is there or not and whether there are any query parameters.

I know exactly what you are trying to do. In order to do it your way just split your string on question mark and then use last item form your array.
var data = your_url.split('?');
var newUrl = '/ajax/projects.php' + (data.length > 1 ? data[length-1] : "");
and you will have your url.
But what you can do is execute same url using your Script just add one parameter IsAjax=true and then check it in codebehind and execute your ajax logic.
e.g.
$('#somelink').onclick(function(){
$.ajax({ url: $(this).href, data { IsAjax: true } .... }
});
Using this way you will have more robust app.

I'll assume that by
http://www.example.com/members/admin/messages/
should return...
/ajax/members.php
you meant - should return...
/ajax/messages.php
If that is the case try
var query = url.split('?');
var paths = query[0].split('/');
var path = paths.pop();
if (path == '') //when there is trailing slash
path = paths.pop();
if (query.length == 1) //no query string
newurl = '/ajax/' + path + '.php';
else //query string
newurl = '/ajax/' + path + '.php?' + query[1];
I'm sure it can be made simpler and better, but that might give you a start.

var str = "http://www.example.com/members/admin/projects/?projectid=41";
var newStr = "/ajax/" + str.split("/").slice(-2).join(".php");
console.log(newStr);

how do I capture something after something else? like a referer=someString

I have ref=Apple
and my current regex is
var regex = /ref=(.+)/;
var ref = regex.exec(window.location.href);
alert(ref[0]);
but that includes the ref=
now, I also want to stop capturing characters if a & is at the end of the ref param. cause ref may not always be the last param in the url.

You'll want to split the url parameters, rather than using a regular expression.
Something like:
var get = window.location.href.split('?')[1];
var params = get.split('&');
for (p in params) {
var key = params[p].split('=')[0];
var value = params[p].split('=')[1];
if (key == 'ref') {
alert('ref is ' + value);
}
}

Use ref[1] instead.
This accesses what is captured by group 1 in your pattern.
Note that there's almost certainly a better way to do key/value parsing in Javascript than regex.
References
regular-expressions.info/Brackets for Capturing

You are using the ref wrong, you should use ref[1] for the (.+), ref[0] is the whole match.
If & is at the end, modify the regexp to /ref=([^&]+)/, to exclude &s.
Also, make sure you urldecode (unescape in JavaScript) the match.

Capture only word characters and numbers:
var regex = /ref=(\w+)/;
var ref = regex.exec(window.location.href);
alert(ref[1]);
Capture word characters, numbers, - and _:
var regex = /ref=([\w_\-]+)/;
var ref = regex.exec(window.location.href);
alert(ref[1]);
More information about Regular Expressions (the basics)

try this regex pattern ref=(.*?)&
This pattern will match anything after ref= and stop before '&'
To get the value of m just use following code:
var regex = /ref=(.*?)&/;
var ref = regex.exec(window.location.href);
alert(ref[1]);