<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-js -->
var first = [true,false]; var second = [true,true];
var result = first.map((aVal, aIndex) => aVal && second[aIndex]);
console.log(result);
<!-- end snippet -->

<!-- begin snippet: js hide: false console: true babel: false -->
<!-- language: lang-js -->
var myJSONObject = {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"}; delete myJSONObject.regex;
console.log ( myJSONObject.regex); // logs: undefined
<!-- end snippet -->
This works in Firefox and Internet&nbsp;Explorer, and I think it works in all others.