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JS - Nothing to repeat In match function

The error is simple. In JS I try to do somtehing to similar a preg_match in PHP. I found match function. I use this function to compare a value with strings elements. If found something return true, else return false.
I tried this
var sim_action = $(this);
if(sim_action.data("phone").toString().match("/^(+34|0034|34)+([67]){8})$/")){
But return this error.
Invalid regular expression: //^(+34|0034|34)+([67]){8})$//: Nothing
to repeat
So the question is. How can i add this string in JS match function?

You need to escape the + characters with a backslash: /^(\+34|0034|34)\+([67]){8})$/. You also have a closing bracket which doesn't have a matching opening bracket.

+ and () are metacharacters and if you want to refer to the literal, you need to escape them with a \. Here's a regex101 demo which highlights the errors with your regex
As for the regex, from wikipedia, I gather that spanish phone numbers have the format +34(6|7)xxxxxxxx
You can use this regex: /^(\+34|0034|34)[67]\d{8}$/
If you just want to check if the regex passes , you can use regex.test(<stringToBeTested>)
const regex = /^(\+34|0034|34)[67]\d{8}$/
const phone = "+34712345673";
if (regex.test(phone))
console.log("Valid phone number")
const phoneNumbers = ["+34712345673", "0034612345673", "+34812345673"]
phoneNumbers.forEach(p => console.log(regex.test(p)))

How to allow only certain words consecutively with Regex in javascript

I'm trying to write a regex that will return true if it matches the format below, otherwise, it should return false. It should only allow words as below:
Positive match (return true)
UA-1234-1,UA-12345-2,UA-34578-2
Negative match (return false or null)
Note: A is missing after U
UA-1234-1,U-12345-2
It should always give me true when the string passed to regex is
UA-1234-1,UA-12345-2,UA-34578-2,...........
Below is what I am trying to do but it is matching only the first element and not returning null.
var pattern=/^UA-[0-9]+(-[0-9]+)?/g;
pattern.match("UA-1234-1,UA-12345-2,UA-34578-2");
pattern.exec("UA-1234-1,UA-12345-2,UA-34578-2)
Thanks in advance. Help is greatly appreciated.

The pattern you need is a pattern enclosed with anchors (^ - start of string and $ - end of string) that matches your pattern at first (the initial "block") and then matches 0 or more occurrences of a , followed with the block pattern.
It looks like /^BLOCK(?:,BLOCK)*$/. You may introduce optional whitespaces in between, e.g. /^BLOCK(?:,\s*BLOCK)*$/.
In the end, the pattern looks like ^UA-[0-9]+(?:-[0-9]+)?(?:,UA-[0-9]+(?:-[0-9]+)?)*$. It is best to build it dynamically to keep it readable and easy to maintain:
const block = "UA-[0-9]+(?:-[0-9]+)?";
let rx = new RegExp(`^${block}(?:,${block})*$`); // RegExp("^" + block + "(?:," + block + ")*$") // for non-ES6
let tests = ['UA-1234-1,UA-12345-2,UA-34578-2', 'UA-1234-1,U-12345-2'];
for (var s of tests) {
console.log(s, "=>", rx.test(s));
}

split the string by commas, and test each element instead.

regular expression to extract two items from a long string

There are some strings having the following type of format,
{abc=1234457, cde=3, label=3352-4e9a-9022-1067ca63} <chve> abc? 123.456.789, http=appl.com
I would like to extract 1234457 and 3352-4e9a-9022-1067ca63, which correspond to abc and label respectively.
This is the javascript I have been trying to use, but it does not work. I think the regular expression part is wrong.
var headerPattern = new RegExp("\{abc=([\d]*),,label=(.*)(.*)");
if (headerPattern.test(row)) {
abc = headerPattern.exec(row)[0];
label = headerPattern.exec(row)[1];
}

Try: abc=(\d*).*?label=([^}]*)
Explanation
abc= literal match
(\d*) catch some numbers
.*? Lazy match
label= literal match
([^}]*) catch all the things that aren't the closing brace

Here is what I came up with:
\{abc=(\d+).*label=(.+)\}.*
Your have two problems in \{abc=([\d]*),,label=(.*)(.*):
Using abc=([\d]*),,, you are looking for abc=([\d]*) followed by the literal ,,. You should use .* instead. Since .* is nongreedy be default, it will not match past the label.
By using label=(.*)(.*), the first .* captures all the remaining text. You want to only catch text until the edge of the braces, so use (.*)}.*.
Disclaimer: Made with a Java-based regex tester. If anything in JavaScript regexes would invalidate this, feel free to comment.

You can do it the following way:
var row = '{abc=1234457, cde=3, label=3352-4e9a-9022-1067ca63} <chve> abc? 123.456.789, http=appl.com';
var headerPatternResult = /{abc=([0-9]+),.*?label=([a-z0-9\-]+)}/.exec(row);
if (headerPatternResult !== null) {
var abc = headerPatternResult[1];
var label = headerPatternResult[2];
console.log('abc: ' + abc);
console.log('label: ' + label);
}

How to replace whitespaces using javascript?

I'm trying to remove the whitespaces from a textarea . The below code is not appending the text i'm selecting from two dropdowns. Can somebody tell me where i'd gone wrong? I'm trying to remove multiple spaces within the string as well, will that work with the same? Dont know regular expressions much. Please help.
function addToExpressionPreview() {
var reqColumnName = $('#ddlColumnNames')[0].value;
var reqOperator = $('#ddOperator')[0].value;
var expressionTextArea = document.getElementById("expressionPreview");
var txt = document.createTextNode(reqColumnName + reqOperator.toString());
if (expressionTextArea.value.match(/^\s+$/) != null)
{
expressionTextArea.value = (expressionTextArea.value.replace(/^\W+/, '')).replace(/\W+$/, '');
}
expressionTextArea.appendChild(txt);
}

> function addToExpressionPreview() {
> var reqColumnName = $('#ddlColumnNames')[0].value;
> var reqOperator = $('#ddOperator')[0].value;
You might as well use document.getElementById() for each of the above.
> var expressionTextArea = document.getElementById("expressionPreview");
> var txt = document.createTextNode(reqColumnName + reqOperator.toString());
reqOperator is already a string, and in any case, the use of the + operator will coerce it to String unless all expressions or identifiers involved are Numbers.
> if (expressionTextArea.value.match(/^\s+$/) != null) {
There is no need for match here. I seems like you are trying to see if the value is all whitespace, so you can use:
if (/^\s*$/.test(expressionTextArea.value)) {
// value is empty or all whitespace
Since you re-use expressionTextArea.value several times, it would be much more convenient to store it an a variable, preferably with a short name.
> expressionTextArea.value = (expressionTextArea.value.replace(/^\W+/,
> '')).replace(/\W+$/, '');
That will replace one or more non-word characters at the end of the string with nothing. If you want to replace multiple white space characters anywhere in the string with one, then (note wrapping for posting here):
expressionTextArea.value = expressionTextArea.value.
replace(/^\s+/,'').
replace(/\s+$/, '').
replace(/\s+/g,' ');
Note that \s does not match the same range of 'whitespace' characters in all browsers. However, for simple use for form element values it is probably sufficient.

Whitespace is matched by \s, so
expressionTextArea.value.replace(/\s/g, "");
should do the trick for you.
In your sample, ^\W+ will only match leading characters that are not a word character, and ^\s+$ will only match if the entire string is whitespace. To do a global replace(not just the first match) you need to use the g modifier.

Refer this link, you can get some idea. Try .replace(/ /g,"UrReplacement");
Edit: or .split(' ').join('UrReplacement') if you have an aversion to REs

Remove all special characters with RegExp

I would like a RegExp that will remove all special characters from a string. I am trying something like this but it doesn’t work in IE7, though it works in Firefox.
var specialChars = "!##$^&%*()+=-[]\/{}|:<>?,.";
for (var i = 0; i < specialChars.length; i++) {
stringToReplace = stringToReplace.replace(new RegExp("\\" + specialChars[i], "gi"), "");
}
A detailed description of the RegExp would be helpful as well.

var desired = stringToReplace.replace(/[^\w\s]/gi, '')
As was mentioned in the comments it's easier to do this as a whitelist - replace the characters which aren't in your safelist.
The caret (^) character is the negation of the set [...], gi say global and case-insensitive (the latter is a bit redundant but I wanted to mention it) and the safelist in this example is digits, word characters, underscores (\w) and whitespace (\s).

Note that if you still want to exclude a set, including things like slashes and special characters you can do the following:
var outString = sourceString.replace(/[`~!##$%^&*()_|+\-=?;:'",.<>\{\}\[\]\\\/]/gi, '');
take special note that in order to also include the "minus" character, you need to escape it with a backslash like the latter group. if you don't it will also select 0-9 which is probably undesired.

Plain Javascript regex does not handle Unicode letters.
Do not use [^\w\s], this will remove letters with accents (like àèéìòù), not to mention to Cyrillic or Chinese, letters coming from such languages will be completed removed.
You really don't want remove these letters together with all the special characters. You have two chances:
Add in your regex all the special characters you don't want remove, for example: [^èéòàùì\w\s].
Have a look at xregexp.com. XRegExp adds base support for Unicode matching via the \p{...} syntax.
var str = "Їжак::: résd,$%& adùf"
var search = XRegExp('([^?<first>\\pL ]+)');
var res = XRegExp.replace(str, search, '',"all");
console.log(res); // returns "Їжак::: resd,adf"
console.log(str.replace(/[^\w\s]/gi, '') ); // returns " rsd adf"
console.log(str.replace(/[^\wèéòàùì\s]/gi, '') ); // returns " résd adùf"
<script src="https://cdnjs.cloudflare.com/ajax/libs/xregexp/3.1.1/xregexp-all.js"></script>

using \W or [a-z0-9] regex won't work for non english languages like chinese etc.,
It's better to use all special characters in regex and exclude them from given string
str.replace(/[~`!##$%^&*()+={}\[\];:\'\"<>.,\/\\\?-_]/g, '');

The first solution does not work for any UTF-8 alphabet. (It will cut text such as Їжак). I have managed to create a function which does not use RegExp and use good UTF-8 support in the JavaScript engine. The idea is simple if a symbol is equal in uppercase and lowercase it is a special character. The only exception is made for whitespace.
function removeSpecials(str) {
var lower = str.toLowerCase();
var upper = str.toUpperCase();
var res = "";
for(var i=0; i<lower.length; ++i) {
if(lower[i] != upper[i] || lower[i].trim() === '')
res += str[i];
}
return res;
}
Update: Please note, that this solution works only for languages where there are small and capital letters. In languages like Chinese, this won't work.
Update 2: I came to the original solution when I was working on a fuzzy search. If you also trying to remove special characters to implement search functionality, there is a better approach. Use any transliteration library which will produce you string only from Latin characters and then the simple Regexp will do all magic of removing special characters. (This will work for Chinese also and you also will receive side benefits by making Tromsø == Tromso).

I use RegexBuddy for debbuging my regexes it has almost all languages very usefull. Than copy/paste for the targeted language.
Terrific tool and not very expensive.
So I copy/pasted your regex and your issue is that [,] are special characters in regex, so you need to escape them. So the regex should be : /!##$^&%*()+=-[\x5B\x5D]\/{}|:<>?,./im

str.replace(/\s|[0-9_]|\W|[#$%^&*()]/g, "") I did sth like this.
But there is some people who did it much easier like str.replace(/\W_/g,"");

#Seagull anwser (https://stackoverflow.com/a/26482552/4556619)
looks good but you get undefined string in result when there are some special (turkish) characters. See example below.
let str="bənövşəyi 😟пурпурный İdÖĞ";
i slightly improve it and patch with undefined check.
function removeSpecials(str) {
let lower = str.toLowerCase();
let upper = str.toUpperCase();
let res = "",i=0,n=lower.length,t;
for(i; i<n; ++i) {
if(lower[i] !== upper[i] || lower[i].trim() === ''){
t=str[i];
if(t!==undefined){
res +=t;
}
}
}
return res;
}

text.replace(/[`~!##$%^*()_|+\-=?;:'",.<>\{\}\[\]\\\/]/gi, '');

why dont you do something like:
re = /^[a-z0-9 ]$/i;
var isValid = re.test(yourInput);
to check if your input contain any special char