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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)))

syntax error on function to detect non-alphanumeric characters in a value?

I know that there are hundreds( or likely thousands) of questions regarding regex functions in this forum. I have read and consulted several, and by all presumptions, I ought to have the answer, and my function ought to work, but it isn't.
I have tried to build a function, in which one of the checks is for only allowing alpha-numeric characters.
The abridged version of the code is this:
function functionName() {
var x = $("#inputId").val();
//trying to locate any/all non alphanumeric characters & spaces
var regex = /^[^0-9a-zA-Z\s]+$/g
if ( x.indexOf(regex) >= 0 ){
alert("message");
return false;
}
}
Does anyone know where I am going wrong?
Thanks

You shouldn't be using indexOf; you should be using test. That's also a little bit of a funny regex you're using. I've modified it below to match valid strings instead of invalid.
function functionName(){
var x = $("#inputId").val();
var regex = /^[a-zA-Z0-9]+$/g;
if ( x.test(regex) ){
alert("Only contains alphanumeric characters. No punctuation or spaces!");
} else {
return false;
}
}

You regex matches only strings that consist entirely of invalid characters. What you really want is one matching when there is at least one invalid character
var regex = /[^0-9a-zA-Z\s]/;
if (regex.test(x)) ...

Your are missing the final '}'

What's wrong with my JavaScript regex / regex syntax?

I need a regex to use with javascript/jquery that fits these rules...
it will include 10 digits
if there is a leading 1 or +1 it should be ignored
valid characters allowed in the field are... 0-9,(), and -
I found a regex at Snipplr (the first one), but its not working. First of all, I'm not even sure if that regex fits my rules. Secondly, its allowing inputs like &^%$$#%^adfafsd. I believe the error is in my code not the regex. For example, are there supposed to be quotes around the expression?
Here is the code that is supposed to be validating the phone field...
$('#phone').bind('blur', function() {
var pattern = new RegExp("^(?:\+?1\s*(?:[.-]\s*)?)?(?:\(\s*([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9])\s*\)|([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9]))\s*(?:[.-]\s*)?([2-9]1[02-9]|[2-9][02-9]1|[2-9][02-9]{2})\s*(?:[.-]\s*)?([0-9]{4})$");
if(pattern.test($('#phone').val())){
$("#phone").addClass("error");
return false;
}else{
$("#phone").removeClass("error");
return true;
}
return true;
})

When you're not using the literal form ( /[regex]/ ), you need to escape the regex string. Try this instead:
var regex = /^(?:\+?1\s*(?:[.-]\s*)?)?(?:\(\s*([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9])\s*\)|([2-9]1[02-9]|[2-9][02-8]1|[2-9][02-8][02-9]))\s*(?:[.-]\s*)?([2-9]1[02-9]|[2-9][02-9]1|[2-9][02-9]{2})\s*(?:[.-]\s*)?([0-9]{4})$/;
if(regex.test($('#phone').val()){ ... }

if there is a leading 1 or +1 it should be ignored
it will include 10 digits
valid characters allowed in the field are... 0-9,(), and -
That could be matched with an expression like:
/^(?:\+?1)?[()-]*(?:\d[()-]*){10}$/

jQuery input filter for textarea

I adapted this solution into my script. The idea is to prevent the user from typing unauthorized characters (of course there is also a filter on the back end).
$('#someinput').keyup(function() {
var $th = $(this);
$th.val( $th.val().replace(/[^a-zA-Z0-9]/g, function(str) {
console.log(str);
return '';
}))
})
It works nice, but I also need the users to be able to type specific allowed characters like: .,!?ñáéíóú - I mean, the basic a-zA-Z0-9 plus some basic chars and the whole bunch of special language characters.
What actually needs to be left out are: ##$%^&*()=_+"':;/<>\|{}[]
Any ideas? Thanks!
Solution thanks to Michael
//query
$('#someinput').keyup(function() {
var $th = $(this);
$th.val($th.val().replace(/[##$%\^&*()=_+"':;\/<>\\\|{}\[\]]/g,function(str){return '';}));
}).bind('paste',function(e) {
setTimeout(function() {
$('#someinput').val($('#someinput').val().replace(/[##$%\^&*()=_+"':;\/<>\\\|{}\[\]]/g,function(str){return '';}));
$('#someinput').val($('#someinput').val().replace(/\s+/g,' '));
},100);
});

Invert your regular expression to only replace the specific characters you want omitted:
$th.val( $th.val().replace(/\s?[##$%\^&*()=_+"':;\/<>\\\|{}\[\]]/g, ""));
// Edit: added optional \s to replace spaces after special chars
Note, a few of them need to be escaped with a backslash inside a [] character class: \\\[\]\^\/

If I'm understanding what you are wanting to do, can't you just add those unwanted characters to your regex instead of doing the [^a-zA-Z0-9]?
Replace that with [##\$%\^&\*\(\)=_\+"':;\/<>\\\|\{\}\[\]] (notice the escaping)

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