2020 - JS interview - tasks

1)
You are given an array of servers that start to crash from some server.
The server health check runs asynchronously and returns a Promise <boolean>.
Only one server can be checked for operability at a time.
It is necessary to write the findServer function, which will receive a list of servers and function functions as input,
but it will return a Promise, which will be resolved with the address of the first failed server.
The solution should run the check function as few times as possible.
Async / await and generators cannot be used.

Example
const servers = ['srv-a', 'srv-b', 'srv-c', 'srv-d'];
const check = (name) => new Promise((res) => setTimeout(res, 100)).then(() => name === 'srv-a');

findServer(servers, check); // Promise.resolve('srv-b')

2)
You need to implement the method
load (url, priority) returns Promise
The load method works according to the following logic - the resource starts loading only then,
when we received a response from all resources previously requested with a higher priority.
If no resources are loaded at the time of the call or their priority is lower or equal to priority -
you need to start downloading immediately.
It is guaranteed that there will be no calls with different priority values for the same url.

3)
You need to write a function that converts a string from Camel Case to Snake Case.
Examples:
camelToSnake ('updatedAt') // updated_at
camelToSnake ('XmlHttpRequest') // xml_http_request