javascript - 检查键是否存在于JavaScript对象中？(Checking if a key exists in a JavaScript object?)

Question

How do I check if a particular key exists in a JavaScript object or array?

(如何检查JavaScript对象或数组中是否存在特定键？)

If a key doesn't exist, and I try to access it, will it return false?

(如果密钥不存在，而我尝试访问它，它将返回false吗？)

Or throw an error?

(还是抛出错误？)

  ask by Adam Ernst translate from so