promise/no-nesting Style

🚧 An auto-fix is still under development.

What it does

Disallow nested then() or catch() statements.

Why is this bad?

Nesting promises makes code harder to read and understand.

Examples

Examples of incorrect code for this rule:

doThing().then(() => a.then());

doThing().then(function() {
  a.then();
});

doThing().then(() => {
  b.catch();
});

doThing().catch((val) => doSomething(val).catch(errors));

Examples of correct code for this rule:

doThing().then(() => 4);

doThing().then(function() {
  return 4;
});

doThing().catch(() => 4);

doThing()
  .then(() => Promise.resolve(1))
  .then(() => Promise.resolve(2));

This example is not a rule violation as unnesting here would result in a being undefined in the expression getC(a, b).

doThing()
  .then(a =>
    getB(a)
      .then(b => getC(a, b))
  );

How to use

To enable this rule in the CLI or using the config file, you can use:

CLI

oxlint --deny promise/no-nesting --promise-plugin

Config (.oxlintrc.json)

{
  "plugins": ["promise"],
  "rules": {
    "promise/no-nesting": "error"
  }
}

References

• Rule Source