Question

Is it possible to minify a DOM-reference with variable declaration?

For example document.documentElement:

var d = document;
console.log(d[d + 'Element']); // undefined
console.log(d[d] + 'Element'); // undefinedElement

Why does this not work?

Answer 1

It doesn’t work because the string value of the document object is not the string 'document', it’s something like '[object HTMLDocument]' (may vary between browsers).

When you concatentate the string 'Element' with the document object, the object is implicitly converted to a string, and you get a string like '[object HTMLDocument]Element', and document['[object HTMLDocument]Element'] is undefined.