Ruby equivalent to JS

Question

Is there an expression in Ruby equivalent to JavaScript's for:

myHash[id] = myHash[id] || {};

This is usually used when trying to append an array or hash to an existing one but we don't know if it was already created or is the first iteration.

• Carcigenicate: Don't know Ruby, but wouldn't just it's logical OR work? Does it return a boolean value or the first truthy value?
• engineersmnky: myHash[id] ||= {} is the equivalent
• the Tin Man: Please do not use salutations like "hi", valedictions ("thanks!") or signatures. Stack Overflow is not a discussion list, it's an online reference. Also, grammar, spelling and punctuation are all significant.

Answer 1

In Ruby, this code actually works the same as in JavaScript:

myHash[id] = myHash[id] || {}

That being said, the more eloquent way of doing it is:

myHash[id] ||= {}

Answer 2

While these are equivalent:

my_hash[:id] = my_hash[:id] || {} 
my_hash[:id] ||= {} 

You'll find this useful:

require 'fruity'
my_hash = {}
compare do
 test1 { my_hash[:id] = my_hash[:id] || {} }
 test2 { my_hash[:id] ||= {} }
end
# >> Running each test 32768 times. Test will take about 1 second.
# >> test2 is faster than test1 by 2x ± 0.1

Between the two, the second, test2, is idiomatic Ruby, so, while the difference in speed is slight, it adds up. It's also the Ruby way.