Split a string by commas but ignore commas within double-quotes using Javascript

Here is a JavaScript function to do it:

function splitCSVButIgnoreCommasInDoublequotes(str) {  
    //split the str first  
    //then merge the elments between two double quotes  
    var delimiter = ',';  
    var quotes = '"';  
    var elements = str.split(delimiter);  
    var newElements = [];  
    for (var i = 0; i < elements.length; ++i) {  
        if (elements[i].indexOf(quotes) >= 0) {//the left double quotes is found  
            var indexOfRightQuotes = -1;  
            var tmp = elements[i];  
            //find the right double quotes  
            for (var j = i + 1; j < elements.length; ++j) {  
                if (elements[j].indexOf(quotes) >= 0) {  
                    indexOfRightQuotes = j; 
                    break;
                }  
            }  
            //found the right double quotes  
            //merge all the elements between double quotes  
            if (-1 != indexOfRightQuotes) {   
                for (var j = i + 1; j <= indexOfRightQuotes; ++j) {  
                    tmp = tmp + delimiter + elements[j];  
                }  
                newElements.push(tmp);  
                i = indexOfRightQuotes;  
            }  
            else { //right double quotes is not found  
                newElements.push(elements[i]);  
            }  
        }  
        else {//no left double quotes is found  
            newElements.push(elements[i]);  
        }  
    }  

    return newElements;  
}  

regex: /,(?=(?:(?:[^"]*"){2})*[^"]*$)/

const input_line = '"2C95699FFC68","201 S BOULEVARDRICHMOND, VA 23220","8299600062754882","2018-09-23"'

let my_split = input_line.split(/,(?=(?:(?:[^"]*"){2})*[^"]*$)/)[4]

Output: 
my_split[0]: "2C95699FFC68", 
my_split[1]: "201 S BOULEVARDRICHMOND, VA 23220", 
my_split[2]: "8299600062754882", 
my_split[3]: "2018-09-23"

Reference following link for an explanation: regexr.com/44u6o

Here's what I would do.

var str = 'a, b, c, "d, e, f", g, h';
var arr = str.match(/(".*?"|[^",\s]+)(?=\s*,|\s*$)/g);

/* will match:

    (
        ".*?"       double quotes + anything but double quotes + double quotes
        |           OR
        [^",\s]+    1 or more characters excl. double quotes, comma or spaces of any kind
    )
    (?=             FOLLOWED BY
        \s*,        0 or more empty spaces and a comma
        |           OR
        \s*$        0 or more empty spaces and nothing else (end of string)
    )
    
*/
arr = arr || [];
// this will prevent JS from throwing an error in
// the below loop when there are no matches
for (var i = 0; i < arr.length; i++) console.log('arr['+i+'] =',arr[i]);

Here's a non-regex one that assumes doublequotes will come in pairs:

function splitCsv(str) {
  return str.split(',').reduce((accum,curr)=>{
    if(accum.isConcatting) {
      accum.soFar[accum.soFar.length-1] += ','+curr
    } else {
      accum.soFar.push(curr)
    }
    if(curr.split('"').length % 2 == 0) {
      accum.isConcatting= !accum.isConcatting
    }
    return accum;
  },{soFar:[],isConcatting:false}).soFar
}

console.log(splitCsv('asdf,"a,d",fdsa'),' should be ',['asdf','"a,d"','fdsa'])
console.log(splitCsv(',asdf,,fds,'),' should be ',['','asdf','','fds',''])
console.log(splitCsv('asdf,"a,,,d",fdsa'),' should be ',['asdf','"a,,,d"','fdsa'])