a lot of attention under the hood

Because one of the original goals of the Node.js project was to allow developers to easily build applications that support server-push capabilities, a lot of attention under the hood is on its asynchronous event-driven I/O (input/output) system that, unlike some other application platforms, does not cause the main application process to pause while waiting for data to be written or read。

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N-UNCOUNT If someone or something is getting attention, they are being dealt with or cared for. 照料

例：

Each year more than two million household injuries need medical attention.

每年有二百多万起在家受伤、需要医疗救治的案例。