Develop Reference

How to remove strings before nth character in a text?

I have a dynamically generated text like this
xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0
How can I remove everything before Map ...? I know there is a hard coded way to do this by using substring() but as I said these strings are dynamic and before Map .. can change so I need to do this dynamically by removing everything before 4th index of - character.

You could remove all four minuses and the characters between from start of the string.
var string = 'xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0',
stripped = string.replace(/^([^-]*-){4}/, '');
console.log(stripped);

I would just find the index of Map and use it to slice the string:
let str = "xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0"
let ind = str.indexOf("Map")
console.log(str.slice(ind))
If you prefer a regex (or you may have occurrences of Map in the prefix) you man match exactly what you want with:
let str = "xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0"
let arr = str.match(/^(?:.+?-){4}(.*)/)
console.log(arr[1])

I would just split on the word Map and take the first index
var splitUp = 'xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0'.split('Map')
var firstPart = splitUp[0]

Uses String.replace with regex expression should be the popular solution.
Based on the OP states: so I need to do this dynamically by removing everything before 4th index of - character.,
I think another solution is split('-') first, then join the strings after 4th -.
let test = 'xxxxxx-xxxx-xxxxx-xxxxx-Map-B-844-0'
console.log(test.split('-').slice(4).join('-'))

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(",");

Extract Fractional Number From String

I have a string that looks something like this
Hey this is my 1.20 string
I'm trying to just extract 1.20 from it.
What's the best way to do this?
I've tried something like this, but I get the value of 1.20,20 rather than just 1.20
var query = $(".query_time").html();
var matches = query.match(/\d.(\d+)/);

The result of the match function is an array, not a string. So simply take
var nb = query.match(/\d.(\d+)/)[0];
BTW, you should also escape the dot if you want to have more precise match :
var nb = query.match(/\d\.(\d+)/)[0];
or this if you want to accept commas (depends on the language) :
var nb = query.match(/\d[\.,](\d+)/)[0];
But the exact regex will be based on your exact needs, of course and to match any number (scientific notation ?) I'd suggest to have a look at more complex regex.

The value of matches is actually [ "1.20", "20" ] (which is an array). If you print it, it will get converted to a string, hence the 1.20,20.
String.match returns null or an array of matches where the first index is the fully matched part and then whichever parts you wanted. So the value you want is matches[0].

Try the following
var nb = query.match(/\d\.\d+/)[0]; // "1.20"
You need to escape . because that stands for any character.
Remove the capture group (\d+) and the second match is not returned
Add [0] index to retrieve the match

How can I parse a value out of a string with javascript?

I a string name content that has inside the text "data-RowKey=xxx". I am trying to get out xxx so I tried the following:
var val = content.substring(12 + content.indexOf("data-RowKey="), 3);
This does not work at all. rather than just get three characters I get a very long string. Can anyone see what I am doing wrong

You're using wrong tool. When you want to capture a data matching some pattern, you should use regular expressions. If your value is exactly three symbols, correct expression would be /data-RowKey=(...)/ with . standing for any symbol and () specifying part to capture.

.substring() [MDN] takes two indexes, .substr() [MDN] takes an index and the length. Try:
var val = content.substr(12 + content.indexOf("data-RowKey="), 3);
If "data-RowKey=xxx" is the whole string, there are various other ways to get xxx:
var val = content.replace('data-RowKey=', '');
var val = content.split('=')[1]; // assuming `=` does not appear in xxx

This works:
var value = content.match(/data-RowKey=(.*)/)[1];
Live DEMO
If there could be values after the xxx, use this:
"data-RowKey=123abc".match(/data-RowKey=(.{3}).*/)[1] // 123

If your rowkey is numeric, this might be best since you get the number as an integer and wouldn't need to convert later:
var val = parseInt( content.split("data-RowKey=")[1] );
If always the three characters and/or no need to convert:
var val = content.split("data-RowKey=")[1].substring(0,3);

Extracting the id in all these cases

How can I always extract the number 11 in all these cases.
id="section-11"
id="test-11"
id="something-11"
I do $(this).attr('id'); then what do I do next?

Many ways to achieve that, one way is to use .split() like:
var id = "section-11";
var number = id.split(/-/)[ 1 ];
alert( number ); // 11

$(this).attr('id').match(/\d+/)[0]
This will pull the first numeric match.

Assuming that those last two digits are going to be the only numbers in the id, here's a regex replace to do it:
var id = 'something-11';
var num = id.replace(/\D/g,'');
alert(num);
The above deletes all non-numeric characters from the string.
jsfiddle example

var id = parseInt($(this).attr('id).substring($(this).attr('id').lastIndexOf('-')+1));
The .split() example above also works, but you'll need to grab the highest index in the array, in case you name an id with more than 1 dash: sub-section-11

you can split the string to an array by "-", then you will get the id from the second place of the array.