As you know, replace() function is used to replace value in a given string. It also takes regex as parameter to perform the search for replacement. With regex, you can perform 2 kinds of searches, global case-sensitive and global case-insensitive. For global case-sensitive search, we add g at the end of regex and for global case-insensitive search, we add gi at the end of regex. Example of both scenarios is given below.
var myString = "Green man running on a green grass with green bag.";
var sensitive = myString.replace(/green/g, "red");
document.write(sensitive + "<br>");
var insensitive = myString.replace(/green/gi, "red");