JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<body>

<p>Click the button to replace variable's names with "[Michael and " + variable's name + "]" in the paragraph below:</p>

<p id="demo">int value1 = 0;
int value2=0;
long longvalue =0;
long verylongvalue=0;</p>

<button onclick="myFunction()">Try it</button>

<script>
function myFunction() {
	var var_type = ["long", "String"];
    var var_type2 = "int";
    var str = document.getElementById("demo").innerHTML; 
    var regexpString="(\\bint\\b";
    var_type.map(function(type){
    	console.log(type);
    	regexpString += "\|\\b"+type+"\\b";
    });
    regexpString += ")\\s\*(\?\<varName\>\\w\+)";
    //var original_regexp= "\\b"+var_type2+"\\b\\s\*(\?\<varName\>\\S\+)";
   var regexp = new RegExp(regexpString, 'g');
   var match = regexp.exec(str);
    console.log(match);
    if(match==null){
    	console.log('no match found');
    }else{
    var regexp2 = new RegExp("\\b"+match[2]+"\\b", 'g');
    var res2 = str.replace(regexp2, "[Michael and $&]");
   while(match !== null) {
      console.log(match[2]);
      match = regexp.exec(str);
      if(match != null){
        regexp2 = new RegExp("\\b"+match[2]+"\\b", 'g');
        res2 = res2.replace(regexp2, "[Michael and $&]");
      }
	}
    document.getElementById("demo").innerHTML = res2;
 }
}
</script>

</body>
</html>