Use Your Chains Buddy (JS Exam)

function solve(args) {
    var inputHTML = args[0];
    var res = inputHTML.match(/<p>(.+?)<\/p>/mg);
    var individuals = [];
    for (var match in res) {
        individuals.push(res[match].replace('<p>', '').replace('</p>', '').replace(/[^a-z\d]+/g, ' '));
    }
    var concatStr = individuals.join('');
    var finalStrArr = [];
    for (var symbol in concatStr) {
        var currSymbolCode = concatStr.toUpperCase().charCodeAt(symbol);
        if (currSymbolCode >= 65 && currSymbolCode <= 77) {
            finalStrArr.push(String.fromCharCode(concatStr.charCodeAt(symbol) + 13));
        }
        else if (currSymbolCode > 77 && currSymbolCode <= 90) {
            finalStrArr.push(String.fromCharCode(concatStr.charCodeAt(symbol) - 13));
        }
        else {
            finalStrArr.push(concatStr.charAt(symbol));
        }
    }
    console.log(finalStrArr.join('').replace(/\s+/g, ' '));
}