JSFiddle - React, Tailwind, and code Playground

JavaScript

if (!String.prototype.toTitleCase) {
    String.prototype.toTitleCase = function() {
        return this.charAt(0).toUpperCase() + this.substring(1).toLowerCase();
    }
}

function getSearchTerms(link) {
    link = link.substring(link.indexOf("=") + 1);

    var arr = link.split("+");
    for (var i = 0; i < arr.length; i++) {
        arr[i] = arr[i].toTitleCase();
    }

    return arr.join(" ");
}

document.body.innerHTML = getSearchTerms("q=javascript+stackoverflow+HELP");