Referencing complex variables in JavaScript

Question

How do you make the following JS variable references:

1. When you have an array ( x[0], x[1], ... ), and you have a button like so:

    <button onclick="say(0)"></button> 

   The function looks like this:

    function say(src){ // Define the box (some random div element will do) var box = document.querySelector('#box'); // This is wrong, I know... I need to refer to the variable 'response[0]' in this case... box.innerHTML = response[src]; } 

2. When you have the following list of variables:

    var book = "Some Book"; var shelf = "Some Shelf" var bookshelf = "The cake!" 

In this case, if I want to (for whatever reason) refer to the variable bookshelf , how do I do it by combining the variable names of the other two variables?

I mean, I can't do var x = book + shelf; since that will give me the result = "Some BookSome Shelf" .

Answer 1

Don't make them variables, make them properties of an object:

var tags = {
   book: 'Some book',
   shelf: 'Some shelf',
   bookshelf: 'The Cake!'
};

var which = 'bookshelf';
var x = tags[which];

Answer 2

You'll probably want to make them properties of an object (although they're probably already properties of the window object):

var stuff = {
    book: "Some book!",
    shelf: "Some shelf",
    bookshelf: "The cake!"
};

function say(src) {
    // Define the box (some random div element will do)
    var box = document.querySelector('#box');

    box.innerHTML = stuff[response[src]];
}