You could use the encodeURIComponent function which will properly URL encode the value.

There are two approaches I would consider for this.

1. Strip off the # and everything that follows.

   var number = sPageUrl.substring(0, sPageUrl.indexOf('#'));
   alert(number);
   

2. Split on the # so you have that information when you want it.

   var number = sPageUrl.split('#'),
       url,
       hash;
   
   if (number.length > 1) {
       url = number[0];
       hash = number[1];
   }
   alert(url);
   

Bonus: Both of these approaches also work well for dealing with QueryStrings.

If it's not something very generic and you have special characters and phrases that you want to replace, you could map your special characters/phrases to their replacements and then decode the string and replace each of them:

var replacements = {
    "créer" : "créer", // this is a phrase
    "Ã" : "é",
    "Â" : "e",
    "©" : ""
};
var url = "http://172.23.113.79/recherche/pages/Results.aspx?k=**cr%c3%83%c2%a9er***";
var decoded = unescape(url); // or decodeURI(url);
for(var key in replacements)
    decoded = decoded.replace(key,replacements[key]);

you can remove unwanted characters by adapting the parameters right before passing it into the parser like:

let adaptedParams = params.reduce(into: String: String) { $0[$1.key] = $1.value.joined(separator: ",") }

You can use str.replace(/[^a-zA-Z ]/g, "") to filter string characters other than special charactes. But this will leave empty spaces so you can further add .replace( / +/g, ' ' ) to just get one space if there is more than one

var str = "₳This ฿ was ￠ ₡ a dummy ¢ ₢ ₵ ₫ € ￡ text£ ₤ ₣ ƒin string ₲ ₭ ₥ ₦ ₱ ＄ $ ₮ ₩ ￦ ¥ ￥ ₴ ¤ ₰containing  ៛ ₪ ₯ ₠ ₧ ₨ may௹ ﷼ ㍐ ৲special ৳ ₹ characters"
 
console.log(str.replace(/[^a-zA-Z ]/g, "").replace( / +/g, ' ' ))

For Windows filenames, I believe a simplified version of the .replace should be
.replace(/[\\/:"*?<>|]/g, '')

And what about:

<?php
$query_string = 'foo=' . urlencode($foo) . '&bar=' . urlencode($bar);
echo '<a href="mycgi?' . htmlentities($query_string) . '">';
?>

From: http://php.net/manual/en/function.urlencode.php

To be safe and ensure that you've escaped all the reserved characters specified in both RFC 1738 and RFC 3986 you should use a combination of encodeURIComponent, escape and a replace for the asterisk('*') like this:

encoded = encodeURIComponent( parm ).replace(/[!'()]/g, escape).replace(/\*/g, "%2A");

[Explanation] While RFC 1738: Uniform Resource Locators (URL) specifies that the *, !, ', ( and ) characters may be left unencoded in the URL,

Thus, only alphanumerics, the special characters "$-_.+!*'(),", and reserved characters used for their reserved purposes may be used unencoded within a URL.

RFC 3986, pages 12-13, states that these special characters are reserved as sub-delimiters.

reserved = gen-delims / sub-delims

gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"

sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="

The escape() function has been deprecated but can be used to URL encode the exclamation mark, single quote, left parenthesis and right parenthesis. And since there is some ambiguity on whether an asterisk must be encoded in a URL, and it doesn't hurt to encode, it you can explicitly encode is using something like the replace() function call. [Note that the escape() function is being passed as the second parameter to the first replace() function call. As used here, replace calls the escape() function once for each matched special character of !, ', ( or ), and escape merely returns the 'escape sequence' for that character back to replace, which reassembles any escaped characters with the other fragments.]

Also see 'https://stackoverflow.com/questions/6533561/urlencode-the-asterisk-star-character'

Also while some websites have even identified the asterkisk(*) as being a reserved character under RFC3986, they don't include it in their URL component encoding tool.

Unencoded URL parms:

parm1=this is a test of encoding !@#$%^&*()'
parm2=note that * is not encoded

Encoded URL parms:

parm1=this+is+a+test+of+encoding+%21%40%23%24%25%5E%26*%28%29%27
parm2=note+that+*+is+not+encodeds+not+encoded

You can also use URLSearchParams along with decodeURIComponent.

Personally I prefer URLSearchParams.

From my testing, decodeURIComponent literally just strips/replaces the URI encodes, but URLSearchParams only returns the values of specific querystrings and allows methods to get specific key/value pairs like below.

Example:

var querystring = "?foo=bar%20baz";
var decoded = decodeURIComponent(querystring)
console.log('decoded:');
console.log(decoded)
var urlParams = new URLSearchParams(querystring);
var foo = urlParams.get('foo');
console.log('foo:');
console.log(foo)