Develop Reference

Why is JavaScript's split() method not splitting on ":"?

So to start off, a bit of context. I am pulling data from the following url: "https://webster.cs.washington.edu/pokedex/pokedex.php?pokedex=all" using a GET method. The data returned is a series of Pokemon names and image names in the following format.
Name1:name1.png
Name2:name2.png
...
The list is 151 items long. When I call the typeOf() method "String" is returned, so I am fairly certain it is a String I am dealing with here. What I would like to do is split the String on the delimiters of "\n" and ":".
What I would like:
Name1,name1.png,Name2,name2.png...
After some experimentation with Regex, I found that the Regex to do this was "\n|:". Using this I wrote the following line to split the String apart. I tested this Regex on https://regex101.com and it seems to work properly there.
var splitData = data.split("\n|:");
("data" is the String I receive from the url.)
But instead of splitting the String and placing the substrings into an array it doesn't do anything. (At least as far as I can see.) As such my next idea was to try replacing the characters that were giving me trouble with another character and then splitting on that new character.
data = data.replace("\n", " ");
data = data.replace("/:/g", " ");
var splitData = data.split(" ");
The first line that replaces new line characters does work, but the second line to replace the ":" does not seem to do anything. So I end up with an array that is filled with Strings that look like this.
Name1:name1.png
I can split these strings by calling their index and then splitting the substring stored within, which only confuses me more.
data = data.replace("\n", " ");
var splitData = data.split(" ");
alert(splitData[0].split(":")[1]);
The above code returns "name1.png".
Am I missing something regarding the split() method? Is my Regex wrong? Is there a better way to achieve what I am attempting to do?

Right now you are splitting on the string literal "\n|:" but to do a regex you want data.split(/[:\n]/)
The MDN page shows two ways to build a Regex:
var regex1 = /\w+/;
var regex2 = new RegExp('\\w+');

The following test script was able to work for me. I decided to use the regex in the split instead of trying to replace tokens in the string. It seemed to do the trick for me.
let testResponse = `Abra:abra.png
Aerodactyl:aerodactyl.png`;
let dataArray = testResponse.split(/\n|:/g);
let commaSeperated = dataArray.join(',');
console.log(commaSeperated);

So you can simply use regex by excluding the quotes all together.
You can look at the documentation here for regular expressions. They give the following examples:
var re = /ab+c/;
var re = new RegExp('ab+c');
See below for your expected output:
var data = `Name1:name1.png
Name2:name2.png`;
var splitData = data.split(/[\n:]/);
console.log(splitData);
//Join them by a comma to get all results
console.log(splitData.join(','));
//For some nice key value pairs, you can reduce the array into an object:
var kvps = data.split("\n").reduce((res, line) => {
var split = line.split(':');
return {
...res,
[split[0]]: split[1]
};
}, {});
console.log(kvps);

I tried and this works good.
str.split(/[:\n]/)
Here is a plunker.
plunker

Extract Twitter handlers from string using regex in JavaScript

I Would like to extract the Twitter handler names from a text string, using a regex. I believe I am almost there, except for the ">" that I am including in my output. How can I change my regex to be better, and drop the ">" from my output?
Here is an example of a text string value:
"PlaymakersZA, Absa, DiepslootMTB"
The desired output would be an array consisting of the following:
PlaymakersZA, Absa, DiepslootMTB
Here is an example of my regex:
var array = str.match(/>[a-z-_]+/ig)
Thank you!

You can use match groups in your regex to indicate the part you wish to extract.
I set up this JSFiddle to demonstrate.
Basically, you surround the part of the regex that you want to extract in parenthesis: />([a-z-_]+)/ig, save it as an object, and execute .exec() as long as there are still values. Using index 1 from the resulting array, you can find the first match group's result. Index 0 is the whole regex, and next indices would be subsequent match groups, if available.
var str = "PlaymakersZA, Absa, DiepslootMTB";
var regex = />([a-z-_]+)/ig
var array = regex.exec(str);
while (array != null) {
alert(array[1]);
array = regex.exec(str);
}

You could just strip all the HTML
var str = "PlaymakersZA, Absa, DiepslootMTB";
$handlers = str.replace(/<[^>]*>|\s/g,'').split(",");

RegExp to filter characters after the last dot

For example, I have a string "esolri.gbn43sh.earbnf", and I want to remove every character after the last dot(i.e. "esolri.gbn43sh"). How can I do so with regular expression?
I could of course use non-RegExp way to do it, for example:
"esolri.gbn43sh.earbnf".slice("esolri.gbn43sh.earbnf".lastIndexOf(".")+1);
But I want a regular expression.
I tried /\..*?/, but that remove the first dot instead.
I am using Javascript. Any help is much appreciated.

I would use standard js rather than regex for this one, as it will be easier for others to understand your code
var str = 'esolri.gbn43sh.earbnf'
console.log(
str.slice(str.lastIndexOf('.') + 1)
)

Pattern Matching
Match a dot followed by non-dots until the end of string
let re = /\.[^.]*$/;
Use this with String.prototype.replace to achieve the desired output
'foo.bar.baz'.replace(re, ''); // 'foo.bar'
Other choices
You may find it is more efficient to do a simple substring search for the last . and then use a string slicing method on this index.
let str = 'foo.bar.baz',
i = str.lastIndexOf('.');
if (i !== -1) // i = -1 means no match
str = str.slice(0, i); // "foo.bar"

Regular Expression to get the last word from TitleCase, camelCase

I'm trying to split a TitleCase (or camelCase) string into precisely two parts using javascript. I know I can split it into multiple parts by using the lookahead:
"StringToSplit".split(/(?=[A-Z])/);
And it will make an array ['String', 'To', 'Split']
But what I need is to break it into precisely TWO parts, to produce an array like this:
['StringTo', 'Split']
Where the second element is always the last word in the TitleCase, and the first element is everything else that precedes it.

Is this what you are looking for ?
"StringToSplit".split(/(?=[A-Z][a-z]+$)/); // ["StringTo", "Split"]
Improved based on lolol answer :
"StringToSplit".split(/(?=[A-Z][^A-Z]+$)/); // ["StringTo", "Split"]

Use it like this:
s = "StringToSplit";
last = s.replace(/^.*?([A-Z][a-z]+)(?=$)/, '$1'); // Split
first = s.replace(last, ''); // StringTo
tok = [first, last]; // ["StringTo", "Split"]

You could use
(function(){
return [this.slice(0,this.length-1).join(''), this[this.length-1]];
}).call("StringToSplit".split(/(?=[A-Z])/));
//=> ["StringTo", "Split"]
In [other] words:
create the Array using split from a String
join a slice of that Array without the last element of that
Array
add that and the last element to a final Array

javascript spilt to get part of the word

I tried use javascript spilt to get part of the word : new from What#a_new%20day
I tried code like this:
<script>
var word="What#a_new%20day";
var newword = word.split("%20", 1).split("_", 2);
alert(newword);
</script>
But caused:
Uncaught TypeError: Object What#a_new has no method 'split'
Maybe there have more wiser way to get the word which I need. So can anyone help me? Thanks.

split returns an array, so the second split is trying to operate on the array returned by the first, rather than a string, which causes a TypeError. You'll also want to add the correct index after the second call to split, or newword will also be an array, not the String you're expecting. Change it to:
var newword = word.split("%20", 1)[0].split("_", 2)[1];
This splits word, then splits the string at index 0 of the resulting array, and assigns the value of the string at index 1 of the new array to newword.

Regex to the rescue
var word="What#a_new%20day";
var newword = word.match(/_(.+)%/)[1];
alert(newword);
this returns the first ([1]) captured group ((...)) in the regex (_(.+)%) which is _ followed by any character (.) one or more times (+) followed by %.

the result of a split is an array, not a string. so what you need to do is
<script>
var word="What#a_new%20day";
var newword = word.split("%20", 1)[0].split("_", 2);
alert(newword);
</script>
notice the [0]

split returns an array:
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/split
word.split("%20", 1);
gives an array so you cannot do :
(result from above).split("_", 2);

If split is what your after, go for it, but performance wise, it would be better to do something like this:
var word="What#a_new%20day";
var newword = word.substr(word.indexOf('new'),3)
alert(newword);
Live example: http://jsfiddle.net/qJ8wM/
Split searches for all instances of %20 in the text, whereas indexOf finds the first instance, and substr is fairly cheap performance wise as well.
JsPerf stats on split vs substring (a general case): http://jsperf.com/split-vs-substring