Examples for generating 'Stable, Predictable and Unique' keys

Reconciliation chapter spends a good time explaining why using the index or even Math.random() as a key is a bad idea, proceeding to suggest using an existent id as a key. When there's not an existent id, it's suggested to "add a new ID property to your model or hash some parts of the content to generate a key".

That's a very controversial issue, a lot of people do it wrong. An example of how to do it would make the chapter a lot better. It's an extensive chapter (compared to others) that seems to end up with no code conclusion. 

先閱讀 Reconciliation 章節的「Recursing On Children」部分，以及關於產生唯一 key 的連結討論。為沒有現有 id 的模型確定一個清楚且技術上可靠的範例，然後使用該範例和說明更新該章節；當指南在不依賴不穩定 key 的情況下涵蓋常見陷阱時，即表示完成。