Use if-then-else in promise chains

getArticles()
  .then(conditional()
    .if(data => data.length > 10)
      .then(doIfTrue)
      .then(alsoDoIfTrue)
    .elseIf(data => data.length > 5)
      .then(doIfTrue)
    .else()
      .then(doIfFalse)
    .end())

npm install --save promise-conditional

var conditional = require('promise-conditional')  // Legacy
import conditional from 'promise-conditional'     // ES2015+

It relies on any-promise to find a Promise library. You can use bluebird, q, when, or the native Promise implementation of Node.js or the browser.

conditional()

Starts a condition chain. This is exported via require('promise-conditional').

conditional().if(condition)

Starts an if step. condition is a function that gets the input value. If it returns true, the subsequent then/catch/finally calls will be invoked.

conditional() ... elseIf(condition)

Starts an elseIf step. condition is a function that gets the input value. If it returns true, the subsequent then/catch/finally calls will be invoked, but only if the other if steps have not been invoked.

conditional() ... else()

Starts an else step. The subsequent then/catch/finally calls will be invoked, but only if the other if/elseIf steps have not been invoked.

conditional() ... end()

Returns a function that you can pass onto .then(...) that runs the entire chain.

conditional().if().then(next)

Adds a then/catch/finally step if the last if condition is true.

promise-conditional © 2016+, Rico Sta. Cruz. Released under the MIT License.
Authored and maintained by Rico Sta. Cruz with help from contributors (list).

ricostacruz.com  ·  GitHub @rstacruz  ·  Twitter @rstacruz