// HTMLCollection from getElementsByTagName and getElementsByClassName methods

var a = document.getElementsByTagName('div');
console.log( ({}).toString.call(a) ); // "[object HTMLCollection]"
console.log(typeof a.map); // "undefined"
a = [].slice.call(a); // convert
console.log(typeof a.map); // "function"

// NodeList from querySelectorAll

var b = document.querySelectorAll('div');
console.log( ({}).toString.call(b) ); // "[object NodeList]"
console.log(typeof b.map); // "undefined"
b = [].slice.call(b); // convert
console.log(typeof b.map); // "function"

// childNodes is a NodeList

var c = document.getElementsByTagName('body')[0].childNodes;
console.log( ({}).toString.call(c) ); // "[object NodeList]"