JQuery Regex want to remove commas from string

Use Positive Lookahead ?=

var str = "Andrew,Lucy,,David,Tess,";
str = str.replace(/,(?=,+|$)/g, "");
console.log( str ); // Andrew,Lucy,David,Tess

stop at comma , than lookahead ?= for it's followed by:
,+ one or more commas
| or it's at end of string $

Important

Most probably you'll need to take care for cases when the string starts with one or more commas, than simply append ^,+| to your regex:

var str = ",,Andrew,Lucy,,David,Tess,,";
str = str.replace(/^,+|,(?=,+|$)/g, "");
console.log( str ); // Andrew,Lucy,David,Tess

or respectively /^,+|,(?=,+)|,+$/g

This is a working regex:

/,+(?=,|$)/g

Online Demo

Remove redundant commas followed by a comma or end of line. If you apply this to multiple lines add m (multiline flag) after the closing slash too (otherwise $ matches only at the very end of the text instead of at each newline).

Code Demo

// Add /i at bottom to make the regex it case insensitive
var re = /,+(?=,|$)/g; 

var tests = ['Andrew,Lucy,,David,Tess,','Andrew,,,,Lucy,,,David,Tess,,,'].reverse();
var m;

while( t = tests.pop() ) {
    document.write('"' + t + '" => <font color="green">' + t.replace(re,'') + '</font><br/>');
}

Thanks all. Really appreciate your efforts.

Did something like this. It worked

var your_string = 'Andrew, Lucy,, David, Tess,';
newstr=your_string.replace(',,', ',');

your_string1 = newstr.replace(/[,]$/,'');

first i removed double commas and then i removed comma from the end

Or You can simply use .replace()

var str = "Andrew,Lucy,,David,Tess,";
var res = str.replace(",,", ",").replace(/,\s*$/, ""); 

Working Demo

Without a regex :

var str = "Andrew,Lucy,,David,Tess,";
var res = str.split(",");
res = res.filter(Boolean);
res = res.join(",");
console.log(res);

With a regex and replace function():

var str = "Andrew,Lucy,,David,Tess,";
var res = str.replace(/,,|,$/g, function(x){
  return x == ",," ? ",": "";});
console.log(res);