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How to iterate through multiple lines of input like a matrix, etc.?

I recently started HackerRank and throughout the problems, I've noticed that they often use multiple lines for the input. For example, for the Day 6: Let's Review challenge, the sample input is
2
Hacker
Rank
which is referred to as a string. I want to know if there is a way to iterate by line instead of individual character. This format throws me off on a lot of the exercises, and I want to know if there is a way to make this easier.

You can split() the string by \n
let str = `2
Hacker
Rank`
str = str.split('\n');
str.forEach(x => {
console.log(x);
})

You can use `` to write multiple lines string in Javascript

Regex Delimeter in PapaParse

I wish to ask, is it possible to use regexes as delimiters in PapaParse? Something like:
Papa.parse(string,
{
delimiter:regex
}
);
I am trying to match a specific pattern of CSVs like so:
/([A-Za-z]{2}[0-9]+,?)/g
i.e. I want exactly 2 letters, any amount of numbers, and a comma (or not, in the case of the last element).
Since string.split has a wonderful habit of returning anything but null when nothing matches regex patterns, I was hoping that my answer would lie in PapaParse. If this is not possible, then I would do something more long winded, but hopefully I can be laz-... efficent this time. :)
Trying to do the following:
Papa.parse('ACB5,dsa',{delimiter:'[A-Za-z]{2}[0-9]+,?'});
Results in
["ACB5","dsa"]
Thank you for your time.
edit
Trying out the regex on regexr.com shows that it works with values like
AB544444444444,BC5,
aa5,
At this point, I realize that this was actually a dozy question, considering how a delimiter is the thing that separates what you want to break up.
I'm writing the longer winded version now, so I'll stick that up soon

As Matt (and common sense) rightly say, yes, The delimiter is just ye olde comma. I was looking for a way to separate the results based on a regex, which past me had thought would have some similarity to how string.split works. This is the snippet I was trying to shrink down.
var result = null;
var regex = /([A-Za-z]{2}[0-9]+,?)/g; //Any two letters, a number, and a space
$(document).ready( function() {
$('#inputGraphText').on('input', function(e){ //on text input...
result = $(this).val().split(','); //split using the complex delimiter ','. Also adds a few "" elements to the array for some reason.
var tidy = new Array();
result.forEach(function(elem){
if(elem.search(regex) > -1){
tidy.push(elem.replace('/[, ]/g',''));//Tidy up the result
}
});
$('#first').html(tidy); //place to print out the tidied results
})
});
Obviously , this is not terribly schnazzy (and completely misses out on using PapaParse), but it is what I originally set out to do.
Any better alternatives will take pride of place, but for now, this is fine.
My apologies for the confusion.

How to split a string with the help of JavaScript's regex?

I need to split a string to one or more substrings each of which contains no more or less than two dots. For example, if the string is foo.boo.coo.too" then what would be the regex to get the following array?: ["foo.boo.coo", "boo.coo.too"]. I hope there will be someone to answer this question - I will really admire you, as I've been programming for several years and have not still be used to regular expressions well enough to solve this particular problem by myself. Thank you very much in advance. Let me know your identity so that I can credit you as a contributor of the program I am creating.

RegEx is for this Problem not the best solution a similar problem was discussed here: split-a-sting-every-3-characters-from-back-javascript
A good javascript solution would be a javascript function like this
function splitter(text){
var parts = text.split(".");
var times = parts.length - 2;
var values = [];
for(var index = 0; index<times;index++)
{
values.push(parts.slice(index,index+3).join("."));
}
return values;
}
splitter("too.boo.coo.too")
//=> Result tested on Chrome 25+ ["too.boo.coo", "boo.coo.too"]
I hope this helps
If you want to Use Regex try the Lookhead Stuff, this could help http://www.regular-expressions.info/lookaround.html

Regex by its nature will return non-intersecting results, so if you want "all matches" from a single regex - it's not possible.
So basically you will need to find first match, and then start from next position to find next match and so on; something like this technique described here regex matches with intersection in C# (it's not JavaScript but idea is the same)
You can use the following regex for example:
(?<=^|\.)((?:[^.]*\.){2}[^.]*?)(?=$|\.)
It ensures that it starts and ends with dot, or at begin/end of line, and contains exactly two dots inside, and captures result in first capture. You can replace * with + to make sure at least one symbol exists between dots, if it is required.
But you need to understand that such approach has really bad performance for the task you are solving, so may be using other way (like split + for) will be better solution.

Regex extraction of one letter inside html chunk

Hi need to extract ONE letter from a string.
The string i have is a big block of html, but the part where i need to search in is this text:
Vahvistustunnus M :
And I need to get the M inside the nbsp's
So, who is the quickest regex-guru out there? :)

Ok, according to this page in the molybdenum api docs, the results will be all of the groups concatenated together. Given that you just want the char between the two 's then it's not good enough to match the whole thing and then pull out the group. Instead you'll need to do something like this:
(?<=Vahvistustunnus )[a-zA-Z](?= )
Warning
This might not work for you because lookbehinds (?<=pattern) are not available in all regex flavors. Specifically, i think that because molybdenum is a firefox extension, then it's likely using ECMA (javascript) regex flavor. And ECMA doesn't support lookbehinds.
If that's the case, then i'm gonna have to ask someone else to answer your question as my regex ninja (amateur) skills don't go much further than that. If you were using the regex in javascript code, then there are ways around this limitation, but based on your description, it sounds like you have to solve this problem with nothing but a raw regex?

Looks like it uses JavaScript and if so
var str = "Vahvistustunnus M :";
var patt = "Vahvistustunnus ([A-Z]) :";
var result = str.match(patt)[1];
should work.

Fastest way to remove hyphens from a string

I have IDs that look like: 185-51-671 but they can also have letters at the end, 175-1-7b
All I want to do is remove the hyphens, as a pre-processing step. Show me some cool ways to do this in javascript? I figure there are probably quite a few questions like this one, but I'm interested to see what optimizations people will come up with for "just hyphens"
Thanks!
edit: I am using jQuery, so I guess .replace(a,b) does the trick (replacing a with b)
numberNoHyphens = number.replace("-","");
any other alternatives?
edit #2:
So, just in case anyone is wondering, the correct answer was
numberNoHyphens = number.replace(/-/g,"");
and you need the "g" which is the pattern switch or "global flag" because
numberNoHyphens = number.replace(/-/,"");
will only match and replace the first hyphen

You need to include the global flag:
var str="185-51-671";
var newStr = str.replace(/-/g, "");

This is not faster, but
str.split('-').join('');
should also work.
I set up a jsperf test if anyone wants to add and compare their methods, but it's unlikely anything will be faster than the replace method.
http://jsperf.com/remove-hyphens-from-string

var str='185-51-671';
str=str.replace(/-/g,'');

Gets much easier in String.prototype.replaceAll(). Check out the browser support for the built-in method.
const str = '185-51-671';
console.log(str.replaceAll('-', ''));

Som of these answers, prior to edits, did not remove all of the hyphens. You would need to use .replaceAll("-","")

In tidyverse, there are multiple functions that could suit your needs. Specifically, I would use str_remove, which will replace in a string, the giver character by an empty string (""), effectively removing it (check here the documentation). Example of its usage:
str_remove(x, '-')