JSFiddle - React, Tailwind, and code Playground

by Rahul Desai

JavaScript

var mainString  = "at iteration";

var dynamicString  = "at";  // coming from user input

if(dynamicString .match(/^[a-zA-Z0-9]+$/) // alphanumeric
   || dynamicString .match(/^[a-zA-Z0-9.,]+$/) // alphanumeric followed by . or ,
   || dynamicString .match(/([a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+))/) // email               
    ){
        mainString  = mainString .replace(new RegExp(dynamicString ,"g") , "[]" + dynamicString );
        
    }  

console.log(mainString );