JSFiddle - React, Tailwind, and code Playground

HTML

<div id="result"></div>

JavaScript

var myObj = {
    "strPattern": "Name: #subStr1#<br>Surname: #subStr2#<br>Location: #subStr3#",
    "subStr1": "John",
    "subStr2": "Doe",
    "subStr3": "LA"
};

var html = myObj["strPattern"];

for (var key in myObj) {
   var obj = myObj[key];
    if(key !== "strPattern") {
        html = html.replace("#" + key + "#",obj);
    }
}

jQuery('#result').html(html);