From Api, how to call the data that include the certain string?

I'm the super beginner of Javascript, and the question might be too easy for you.

I have encountered an issue regarding calling the data from API.

When you call a certain data from the description from an API, how would you code to call the information that contains a certain piece of string?

For example, I attempt to call information from the description that includes the string "rain".

            console.log()
            if (data.description === "rain") {
                weatherIcon.className = "wi wi-day-rain"
            } else {
                weatherIcon.className = "wi wi-day-sunny"
            }

I super appreciate in advance.