make example suitable for teenagers/children!?

Maybe that's quite a conservative attempt.
The [*Check for spam* chapter of *Strings*](https://javascript.info/string#check-for-spam) has an example that uses *viagra* and *XXX*.

Considering that nowadays also many young people learn coding on JavvaScript.info I'd personally consider it more suitable (aka. inclusive) for all ages to simple use a different topic that's not so adult-ish.

What do you think?

從 Strings 章節中連結的「Check for spam」部分開始，檢視目前的範例。選擇一個非成人主題，同時保留範例的用途，更新範例，並確認該章節對年輕讀者仍然清楚易懂。

由索引模型根據 Issue 內容生成。