My assumption is that it's setting up an object to map element selectors -> callbacks.
var specialElementHandlers = {
'#editor': function() {
return true;
}
};
But yeah, could be something as
var specialElementHandlers = Object.assign({}, defaultHandlers, {
'#editor': function() {
return true;
}
}; // missing closing parenthesis
If your neighbour's donkey is eating your flowers you're entitled to ask them to move their fat ass.