Always handle Promises

Promises (and async functions which implicitly create Promises) must always be handled at some level of the program, either via:

• using await to wait for the Promise to resolve successfully
• using .then or .catch to handle Promise resolution
• returning a Promise to a calling function which itself has to handle the Promise

Creating a Promise or calling an async function and NOT awaiting or propagating the resulting Promise using one of these approaches is a code smell and violates this rule.

Important: This rule should only apply to function calls which you are 100% sure return a Promise. If you do not know for sure that a function returns a Promise, then disregard it.

Examples

Incorrect Examples

async function saveFile() {
  // ...
}
 
// This is bad because we're not handling the Promise returned by `saveFile`
saveFile()

Correct Examples

async function saveFile() {
  // ...
}
 
// This is fine because we explicitly `await` the Promise returned by `saveFile`
await saveFile()

async function saveFile() {
  // ...
}
 
// This is fine because the Promise returned from `saveFile` is propagated to `main`'s caller
async function main() {
  return saveFile()
}

async function saveFile() {
  // ...
}
 
// This is fine because we explicitly `await` the promise results
await Promise.all([saveFile(), saveFile()])

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