var conwayGame = document.getElementsByClassName('conway-game')[0];
while (conwayGame.firstChild) {
    conwayGame.removeChild(conwayGame.firstChild);
}

> var foo = { foo: 'bar' }
undefined
> foo === { foo: 'bar' }
false
> foo === foo
true

var foo = { foo: 'bar' }
var bar = { foo: 'bar' }
foo === bar

> var foo = { foo: 'bar' }
undefined
> var bar = { foo: 'bar' }
undefined
> foo === bar
false
>

var foo = { foo: 'bar' }
var bar = foo
foo === bar
> true

> var a = new Map();
undefined
> a
Map {}
> var f1 = function(){}
undefined
> var f2 = function(){}
undefined
> a.set(f1, 1)
Map {function function => 1}
> a.get(f2)
undefined
> a.set(f2, 2)
Map {function function => 1, function function => 2}