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Getting the content between two characters

So I have this (example) string: 1234VAR239582358X
And I want to get what's in between VAR and X. I can easily replace it using .replace(/VAR.*X/, "replacement");
But, how would I get the /VAR.*X/as a variable?

I think what you are looking for might be
string.match(/VAR(.*)X/)[1]
The brackets around the .* mark a group. Those groups are returned inside the Array that match creates :)
If you want to only replace what's in between "VAR" and "X" it would be
string.replace(/VAR(.*)X/, "VAR" + "replacement" + "X");
Or more generic:
string.replace(/(VAR).*(X)/, "$1replacement$2");

You can try use the RegExp class, new RegExp(`${VAR}.*X`)

You can store it as variable like this,
const pattern = "VAR.*X";
const reg = new RegExp(pattern);
Then use,
.replace(reg, "replacement");

If you
want to get what's in between VAR and X
then using .* would do the job for the given example string.
But note that is will match until the end of the string, and then backtrack to the first occurrence of X it can match, being the last occurrence of the X char in the string and possible match too much.
If you want to match only the digits, you can match 1+ digits in a capture group using VAR(\d+)X
const regex = /VAR(\d+)X/;
const str = "1234VAR239582358X";
const m = str.match(regex);
if (m) {
let myVariable = m[1];
console.log(myVariable);
}
Or you can match until the first occurrence of an X char using a negated character class VAR([^\r\nX]+)X
const regex = /VAR([^\r\nX]+)X/;
const str = "1234VAR239582358X";
const m = str.match(regex);
if (m) {
let myVariable = m[1];
console.log(myVariable);
}

Remove part of the string before the FIRST dot with js

I have the next problem. I need to remove a part of the string before the first dot in it. I've tried to use split function:
var str = "P001.M003.PO888393";
str = str.split(".").pop();
But the result of str is "PO888393".
I need to remove only the part before the first dot. I want next result: "M003.PO888393".
Someone knows how can I do this? Thanks!

One solution that I can come up with is finding the index of the first period and then extracting the rest of the string from that index+1 using the substring method.
let str = "P001.M003.PO888393";
str = str.substring(str.indexOf('.')+1);
console.log(str)

You can use split and splice function to remove the first entry and use join function to merge the other two strings again as follows:
str = str.split('.').splice(1).join('.');
Result is
M003.PO888393
var str = "P001.M003.PO888393";
str = str.split('.').splice(1).join('.');
console.log(str);

You could use a regular expression with .replace() to match everything from the start of your string up until the first dot ., and replace that with an empty string.
var str = "P001.M003.PO888393";
var res = str.replace(/^[^\.]*\./, '');
console.log(res);
Regex explanation:
^ Match the beginning of the string
[^\.]* match zero or more (*) characters that are not a . character.
\. match a . character
Using these combined matches the first characters in the string include the first ., and replaces it with an empty string ''.

calling replace on the string with regex /^\w+\./g will do it:
let re = /^\w+\./g
let result = "P001.M003.PO888393".replace(re,'')
console.log(result)
where:
\w is word character
+ means one or more times
\. literally .

many way to achieve that:
by using slice function:
let str = "P001.M003.PO888393";
str = str.slice(str.indexOf('.') + 1);
by using substring function
let str = "P001.M003.PO888393";
str = str.substring(str.indexOf('.') + 1);
by using substr function
let str = "P001.M003.PO888393";
str = str.substr(str.indexOf('.') + 1);
and ...

How to replace two characters at the same time with js?

Below is my code.
var str = 'test//123_456';
var new_str = str .replace(/\//g, '').replace(/_/g, '');
console.log(new_str);
It will print test123456 on the screen.
My question is how to do it in same regular express? not replace string twice.
Thanks.

Use character class in the regex to match any character in the collection. Although use repetition (+, 1 or more) for replacing // in a single match.
var new_str = str .replace(/[/_]+/g, '');
var str = 'test//123_456';
var new_str = str.replace(/[/_]+/g, '');
console.log(new_str);
FYI : Inside the character class, there is no need to escape the forward slash(in case of Javascript RegExp).

Use the regex to match the list of character by using regex character class.
var str = "test//123_456";
var nstr = str.replace(/[\/_]/g, '');

Regular Expression to match compound words using only the first word

I am trying to create a regular expression in JS which will match the occurences of box and return the full compound word
Using the string:
the box which is contained within a box-wrap has a box-button
I would like to get:
[box, box-wrap, box-button]
Is this possible to match these words only using the string box?
This is what I have tried so far but it does not return the results I desire.
http://jsfiddle.net/w860xdme/
var str ='the box which is contained within a box-wrap has a box-button';
var regex = new RegExp('([\w-]*box[\w-]*)', 'g');
document.getElementById('output').innerHTML=str.match(regex);

Try this way:
([\w-]*box[\w-]*)
Regex live here.
Requested by comments, here is a working example in javascript:
function my_search(word, sentence) {
var pattern = new RegExp("([\\w-]*" + word + "[\\w-]*)", "gi");
sentence.replace(pattern, function(match) {
document.write(match + "<br>"); // here you can do what do you want
return match;
});
};
var phrase = "the box which is contained within a box-wrap " +
"has a box-button. it is inbox...";
my_search("box", phrase);
Hope it helps.

I'll just throw this out there:
(box[\w-]*)+

You can use this regex in JS:
var w = "box"
var re = new RegExp("\\b" + w + "\\S*");
RegEx Demo

This should work, note the 'W' is upper case.
http://www.w3schools.com/jsref/jsref_obj_regexp.asp
\Wbox\W

It looks like you're wanting to use the match with a regex. Match is a string method that will take a regex as an argument and return an array containing matches.
var str = "your string that contains all of the words you're looking for";
var regex = /you(\S)*(?=\s)/g;
var returnedArray = str.match(regex);
//console.log(returnedArray) returns ['you', 'you\'re']

Javascript replace regex wildcard

I have a string which I need to run a replace.
string = replace('/blogs/1/2/all-blogs/','');
The values 1, 2 and all-blogs can change. Is it possible to make them wildcards?
Thanks in advance,
Regards

You can use .* as a placeholder for "zero or more of any character here" or .+ for "one or more of any character here". I'm not 100% sure exactly what you're trying to do, but for instance:
var str = "/blogs/1/2/all-blogs/";
str = str.replace(/\/blogs\/.+\/.+\/.+\//, '');
alert(str); // Alerts "", the string is now blank
But if there's more after or before it:
str = "foo/blogs/1/2/all-blogs/bar";
str = str.replace(/\/blogs\/.+\/.+\/.+\//, '');
alert(str); // Alerts "foobar"
Live example
Note that in both of the above, only the first match will be replaced. If you wanted to replace all matches, add a g like this:
str = str.replace(/\/blogs\/.+\/.+\/.+\//g, '');
// ^-- here
You can read up on JavaScript's regular expressions on MDC.

js> 'www.google.de/blogs/1/2/all-blogs'.replace(/\/blogs\/[^\/]+\/[^\/]+\/[^\/]+\/?/, '');
www.google.de

What about just splitting the string at slashes and just replacing the values?
var myURL = '/blogs/1/2/all-blogs/', fragments, newURL;
fragments = myURL.split('/');
fragments[1] = 3;
fragments[2] = 8;
fragments[3] = 'some-specific-blog';
newURL = fragments.join('/');
That should return:
'/blogs/3/8/some-specific-blog'

Try this
(/.+){4}
escape as appropriate