syntax - game.HUD = game.HUD || {} meaning

Question

I'm following melon js tutorial. This is at the top of my HUD.js file.

game.HUD = game.HUD || {}

I've seen this before in other examples. What does the namespace.something = namespace.something || {} syntax mean and why is it needed?

Answer 1

||是一个空合并运算符，因此您在该行中说如果它已经存在则返回我的对象​​，如果不存在则返回一个新对象（为空）