Question

Is there some shorthand in Javascript to assign a variable if it evaluates to false?

In ruby I can do this:

foo |= "bar"

Assigns “bar” to foo if foo evaluates to false
so something like this: (using that |= operator)

var cars_by_brand_and_color = {};
for (var car in parking_lot) {
   // add a brand if it doesn't exist yet;
   // cars_by_brand_and_color['chevrolet'] = {};
   cars_by_brand_and_color[car['brand']] |= {};
   // and add that color to the brand if it doesn't exist yet;
   // cars_by_brand_and_color['chevrolet']['grey'] |= {}; 
   cars_by_brand_and_color[car['brand']][car['color']] |= {};
   // now let's add that car; 
   // cars_by_brand_and_color['chevrolet']['grey']['BDB-565'] = 'Mr. Smith';
   cars_by_brand_and_color[car['brand']][car['color']][car['lisence_plate']] = car['owner']
};

Answer 1

Sure, the JS syntax is

var toAssign = mayBeNull || {};