SQL/node_modules/thenify

thenify

Promisify a callback-based function using any-promise.

• Preserves function names
• Uses a native promise implementation if available and tries to fall back to a promise implementation such as bluebird
• Converts multiple arguments from the callback into an Array, also support change the behavior by options.multiArgs
• Resulting function never deoptimizes
• Supports both callback and promise style

An added benefit is that thrown errors in that async function will be caught by the promise!

API

fn = thenify(fn, options)

Promisifies a function.

Options

options are optional.

• options.withCallback - support both callback and promise style, default to false.

• options.multiArgs - change the behavior when callback have multiple arguments. default to true.

  • true - converts multiple arguments to an array
  • false- always use the first argument
  • Array - converts multiple arguments to an object with keys provided in options.multiArgs

• Turn async functions into promises

  var thenify = require('thenify');
  
  var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
  });
  

• Backward compatible with callback

  var thenify = require('thenify');
  
  var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
  }, { withCallback: true });
  
  // somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
  // somethingAsync(a, b, c, function () {});
  

or use thenify.withCallback()

var thenify = require('thenify').withCallback;

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
});

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});

• Always return the first argument in callback

  var thenify = require('thenify');
  
  var promise = thenify(function (callback) {
  callback(null, 1, 2, 3);
  }, { multiArgs: false });
  
  // promise().then(function onFulfilled(value) {
  //   assert.equal(value, 1);
  // });
  

• Converts callback arguments to an object

  var thenify = require('thenify');
  
  var promise = thenify(function (callback) {
  callback(null, 1, 2, 3);
  }, { multiArgs: [ 'one', 'tow', 'three' ] });
  
  // promise().then(function onFulfilled(value) {
  //   assert.deepEqual(value, {
  //     one: 1,
  //     tow: 2,
  //     three: 3
  //   });
  // });