Requests unexpectedly delayed in Javasript

My axios request is taking too much time in sending the request to the server. I have the same issue like this https://github.com/axios/axios/issues/2609

What is this line saying and how can we avoid this mistake in Javascript while sending the request wrapped in promise.

Line: “axios creating a promise under the hood (before sending the request), and the main thread being busy with JavaScript execution”

Can you please tell me some scenerio while when we are doing the same mistake while sending a http request, means keeping the main thread busy?