Implementation of Caesars Cipher for Free Code Camp

caesars-cipher.json

{"index.js":"function rot13(str) { // LBH QVQ VG!\n      return str.split('')\n                .map.call(str, function(char) {\n                    \n                    let x = char.charCodeAt(0);\n           \n                    if (x < 65 || x > 90) {   \n                         return String.fromCharCode(x);\n                    } else if (x < 78) {    \n                         return String.fromCharCode(x + 13); \n                    }\n                    \n                    return String.fromCharCode(x - 13);\n        }).join(''); \n}\n\n// Change the inputs below to test\nrot13(\"SERR PBQR PNZC\");"}