How to implement a promise-based API - Learn web development | MDN

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• The setTimeout() API takes as arguments a callback function and a delay, given in milliseconds. When setTimeout() is called, it starts a timer set to the given delay, and when the time expires, it calls the given function

• The key component here is the Promise() constructor. The Promise() constructor takes a single function as an argument. We'll call this function the executor. When you create a new promise you supply the implementation of the executor.

• This executor function itself takes two arguments, which are both also functions, and which are conventionally called resolve and reject

• How to implement a promise-based API

• Implementing an alarm() API

• Wrapping setTimeout()

• The Promise() constructor

• Using the alarm() API

• Using async and await with the alarm() API