"use strict";

//var str = "(() => { fs = 42 })()"
var str = "fs = 42"
var fs = {};

console.log('pass', !!(str.match(/^\s*\([^)]*\)\s*=>/))) // passing the second regexp test
console.log('fs', fs) // {}
("indirect", eval)(str);
console.log('fs', fs) // 42. The direct-evaled code modified a variable value outside its scope