Chaining API calls

Currently, our app can only handle 5-digit numerical postal or zip codes from the US. A postal code such as 22201 is easy to differentiate from a city name with a simplistic conditional such as typeof search === 'string'. However, postal codes can vary widely from country to country, the UK being a great example, with postal codes such as EC2R 6AB. Even if we had a perfect understanding of how postal codes are formatted for every country, we still couldn’t ensure that the user didn’t fat-finger a slightly incorrect postal code. Today’s sophisticated users expect web applications to be resilient toward such mistakes. However, as web developers, we can’t be expected to code up a universal postal code validation service by hand. Instead, we need to leverage an external service before we send our request to OpenWeatherMap APIs. Let’s explore how we can chain back-to-back API calls that rely on each other.

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