I'm making a toggle in d3, and trying to avoid global variables.

I can go ahead and select the item as though it was already in the scene:

d3.select('#awesome_line_graph')

and then test to see if I caught anything using

if (d3.select('#awesome_line_graph')[0].every(function(d){return d===null})){

    // draw awesome line graph

} else {

    d3.select('#awesome_line_graph').remove()

}

but this testing for the zeroth element for maybe more than one null thing seems terrible and hacky. How should I do it instead? Apologies for not knowing much javascript.