Develop Reference

Is there anyway to simulate a "Did you mean" in Java Script?

So I'm creating a bot with an API, and the list is pretty case sensitive and only allowing exact matches.
For example, there I have the word "ENCHANTED_GLISTERING_MELON". Its all-caps have underscores and complicated spelling, and the site does not accept if it is not an exact match. It is not so user-friendly. Is there any way to so that when a user inputs something, it will auto-capitalize, replace spaces with underscores, and most importantly, check for misspellings, then consider the closest word? I have a dictionary of what the site accepts.

It not a a simple task to disallow some words with typos.
To avoid reinventing the wheel I would recommend you to use the one of the Open Source engines like RASA to enable neural language processing with your chat.
https://rasa.com/
However, it's not so easy to use if you having troubles with parsing the string in JavaScript.
For a words similarities you check Levenshtein Distance algorithm:
https://www.npmjs.com/package/autocorrect
https://www.npmjs.com/package/string-similarity
Getting the closest string match
For a simple solution you can just replace your disallowed words:
How to replace several words in javascript
Also, if it's just a filter for a bad words in your chat you can use some existing libraries like bad-words:
https://www.npmjs.com/package/bad-words
And you can capitalize everything for your particular strange case:
'enchanted glistering melon'.trim().replace(/ /g,'_').toLocaleUpperCase()

Regular expression for retrieving tags

in my project i want to retrieve tags from a web page for that i used dom methods.
But tags can be created dynamically like document.write(“<a href=”http://somedomain.com”>”);
here tags are given in the format of a string so i am trying to use regular expressions.
I want a regular expression which matches all the tags and attributes provided the expression should be able to extract specific attribute also

It is very hard to understand what you are asking and it is very unclear.
First off: never use regex to parse HTML if you have an option. It looks simple right? No. You'll find a problem sooner or later.
Second: what David said.
Now here's a regex to match any HTML tag (have not tested it or anything so try it out first if you must):
\<[^>]*\>
Be warned it will match a script tag too (do not let users write any tag to your page, whitelist a few if you must, and be prepared to have trouble if you don't use a library).
Try these out at RegExr for example (but remind that it uses ActionScript regexes, may be different from Javascript ones sometimes, for example Javascript has no lookahead/lookbehind.

Fulltext search ignoring comments

I want fulltext search for my JavaScript code, but I'm usually not interested in matches from the comments.
How can I have fulltext search ignoring any commented match? Such a feature would increase my productivity as a programmer.
Also, how can I do the opposite: search within the comments only?
(I'm currently using Text Mate, but happy to change.)

See our Source Code Search Engine (SCSE). This tool indexes your code base using the langauge structure to guide the indexing; it can do so for many languages including JavaScript. Search queries are then stated in terms of abstract language tokens, e.g., to find identifiers involving the string "tax" multiplied by some constant, you'd write:
I=*tax* '*' N
This will search all indexed languages only for identifiers (in each language) following by a '*' token, followed by some kind of number. Because the tool understands language structure, it isn't confused by whitespace, formatting or interverning comments. Because it understands comments, you can search inside just comments (say, for authors):
C=*Author*
Given a query, the SCSE finds all the hits across the code base (possibly millions of lines), and offers these as set of choices; clicking on choice pulls up the file with the hit in the middle outlined where the match occurs.
If you insist on searching just raw text, the SCSE provides grep-style searches. If you have only a small set of files, this is still pretty fast. If you have a big set of files, this is a lot slower than language-structure based searches. In both cases, grep like searches get you more hits, usually at the cost of false positives (e.g., finding "tax" in a comment, or finding a variable named "Authorization_code"). But at least you have the choice.
While this doesn't operate from inside an editor, you can launch your editor (for most editors) on a file once you've found the hit you want.

Use ultraedit , It fully supports full text search ignoring comment or also within the comment search

How about NetBeans way (Find Symbol in the Navigate Menu),
It searches all variables,functions,objects etc.
Or you could customize JSLint and customize it if you want to integrate it in a web application or something like that.

I personnaly use Notepad++ wich is a great free code editor. It seems you need an editor supporting regular expression search (in one or many files). If you know Reg you can use powerfull search like in/out javascript comments...the work will be to build the right expression and test it with one file with all differents cases to be sure it will not miss things during real search, or maybe you can google for 'javascript comments regular expression' or something like...
Then must have a look at Notepad++ plugins, one is 'RegEx Helper' wich helps for building regular expressions.

Regular Expression problem

I need a regular expression for javascript that will get "jones.com/ca" from "Hello we are jones.com/ca in Tampa". The "jones.com/ca" could be any web url extension (example: .net, .co, .gov, etc), and any name. So the regular expression needs to find all instances of say ".com" and all the text to the last white space or beginning of line and to the last white space or end of line (minus any ending punctuation).
Right now I have as an example line: "jones.com/ca some text", using a javascript regular expression of: "\\(.+?^\\s).com?([^\\s]+)?\\", and all I get is ".com/ca" as the output.

This example will capture specific domains com,org and gov
\b\w+\.(?:com|org|gov)/[a-z]{2}\b
And this will capture almost any domain
\b\w+\.[a-z]{2,3}/[a-z]{2}\b
It uses word boundaries so that it does not capture white space.

Matching URLs is a bit of a dark art. The following site has a fairly well-designed regex for this purpose: http://daringfireball.net/2010/07/improved_regex_for_matching_urls

A comprehensive regex for this is going to be much more complicated than you think. The list of top-level domains is fairly long (.gov, .info, .edu, .museum, etc.), and there are "special" domains like localhost as well. Also, many domains end in a two-letter country abbreviation (google.com.br for Google Brazil, for example, or del.icio.us).
The easiest thing would be to look for http(s):// or www at the beginning and just assume what comes after is a domain name. If you don't, you're going to either miss a lot, or get a lot of false positives.
You could try the following, but the last option (after the last |) is going to be open to a significant number of false positives:
/https?:\/\/\S+|www\.\S+|([-a-z0-9_]+\.)+(com|org|edu|gov|mil|info|[a-z]{2})(\/\S*)?|([-a-z0-9_]+\.)+[-a-z0-9_]+\/\S*/ig

Javascript/Regex for finding just the root domain name without sub domains

I had a search and found lot's of similar regex examples, but not quite what I need.
I want to be able to pass in the following urls and return the results:
www.google.com returns google.com
sub.domains.are.cool.google.com returns google.com
doesntmatterhowlongasubdomainis.idont.wantit.google.com
returns google.com
sub.domain.google.com/no/thanks returns google.com
Hope that makes sense :)
Thanks in advance!-James

You can't do this with a regular expression because you don't know how many blocks are in the suffix.
For example google.com has a suffix of com. To get from subdomain.google.com to google.com you'd have to take the last two blocks - one for the suffix and one for google.
If you apply this logic to subdomain.google.co.uk though you would end up with co.uk.
You will actually need to look up the suffix from a list like http://publicsuffix.org/

Don't use regex, use the .split() method and work from there.
var s = domain.split('.');
If your use case is fairly narrow you could then check the TLDs as needed, and then return the last 2 or 3 segments as appropriate:
return s.slice(-2).join('.');
It'll make your eyes bleed less than any regex solution.

I've not done a lot of testing on this, but if I understand what you're asking for, this should be a decent starting point...
([A-Za-z0-9-]+\.([A-Za-z]{3,}|[A-Za-z]{2}\.[A-Za-z]{2}|[A-za-z]{2}))\b
EDIT:
To clarify, it's looking for:
one or more alpha-numeric characters or dashes, followed by a literal dot
and then one of three things...
three or more alpha characters (i.e. com/net/mil/coop, etc.)
two alpha characters, followed by a literal dot, followed by two more alphas (i.e. co.uk)
two alpha characters (i.e. us/uk/to, etc)
and at the end of that, a word boundary (\b) meaning the end of the string, a space, or a non-word character (in regex word characters are typically alpha-numerics, and underscore).
As I say, I didn't do much testing, but it seemed a reasonable jumping off point. You'd likely need to try it and tune it some, and even then, it's unlikely that you'll get 100% for all test cases. There are considerations like Unicode domain names and all sorts of technically-valid-but-you'll-likely-not-encounter-in-the-wild things that'll trip up a simple regex like this, but this'll probably get you 90%+ of the way there.

If you have limited subset of data, I suggest to keep the regex simple, e.g.
(([a-z\-]+)(?:\.com|\.fr|\.co.uk))
This will match:
www.google.com --> google.com
www.google.co.uk --> google.co.uk
www.foo-bar.com --> foo-bar.com
In my case, I know that all relevant URLs will be matched using this regex.
Collect a sample dataset and test it against your regex. While prototyping, you can do that using a tool such https://regex101.com/r/aG9uT0/1. In development, automate it using a test script.

([A-Za-z0-9-]+\.([A-Za-z]{3,}|[A-Za-z]{2}\.[A-Za-z]{2}|[A-za-z]{2}))(?!\.([A-Za-z]{3,}|[A-Za-z]{2}\.[A-Za-z]{2}|[A-za-z]{2}))\b
This is an improvement upon theracoonbear's answer.
I did a quick bit of testing and noticed that if you give it a domain where the subdomain has a subdomain, it will fail. I also wanted to point out that the "90%" was definitely not generous. It will be a lot closer to 100% than you think. It works on all subdomains of the top 50 most visited websites which accounts for a huge chunk of worldwide internet activity. The only time it would fail is potentially with unicode domains, etc.
My solution starts off working the same way that theracoonbear's does. Instead of checking for a word boundary, it uses a negative lookahead to check if there is not something that could be a TLD at the end (just copied the TLD checking part over into a negative lookahead).

Without testing the validity of top level domain, I'm using an adaptation of stormsweeper's solution:
domain = 'sub.domains.are.cool.google.com'
s = domain.split('.')
tld = s.slice(-2..-1).join('.')
EDIT: Be careful of issues with three part TLDs like domain.co.uk.