javascript - How to increment an object property value if it exists, else set the initial value?

Question

How might I add check to see if a key already exists, and if does, increment the value, and if it doesn't exist, then set the initial value?

Something like this pseudo-code:

var dict = {};
var new_item = "Bill"

If new_item not in dict:
dict[new_item] = 1

else:

dict[new_item] += 1

Answer 1

dict[key] = (dict[key] || 0) + 1;