A simple script to run asynchronous tasks with auto. Alternative to async.auto

README.md

0tis-autotasks

A simple script to run asynchronous tasks with auto. Alternative to async.auto

Install

npm i -S gist:bf5ff86a2a20f88f3b327872427598ab

How to use

import autoTasks from '0tis-autotasks';
autoTasks({
  one: cb=>cb(null, 1),
  two:['one', (cb, res)=>cb(null, res.one, 2)],
  three: ['one', 'two', (cb, res)=>cb('just error')]
}, (err, data)=>{
  console.log(err, data); //just error {one: 1, two: [1, 2], three: undefined}
})

autoTasks.js

function autoTasks(tasks, callback){
  if(tasks == null) {
    throw new Error('First argument must be an object (but not null)');
  }

  const toDo = [];
  const wait = {};
  const results = {};
  let done = false;

  const call = (key, task, resolve, reject)=>{
    [task] = task;
    try{
      task((err, ...result)=>{
        if(done) return;
        if(result.length < 2) [result] = result;
        results[key] = result;

        if(err){
          return reject(err);
        }

        resolve();

        if(wait[key]){
          wait[key].forEach(check=>check());
        }
        while(run = toDo.shift()){
          run();
        }
      }, results);
    }catch(e){
      reject(e);
    }
  };

  Promise.all(Object.keys(tasks).map(key=>{
    return new Promise((resolve, reject)=>{
      let task = tasks[key];
      if(!Array.isArray(task)) task = [task];
      
      let dependencies = task.splice(0, task.length-1);
      if(dependencies.length){
        dependencies.forEach(dependency=>{
          if(!tasks[dependency]){
            throw new Error(`Task "${key}" have dependency "${dependency}" that not presented in object`);
          }

          if(!wait[dependency]) wait[dependency] = [];
          wait[dependency].push(()=>{
            dependencies = dependencies.filter(dep=>dep !== dependency);
            if(!dependencies.length){
              toDo.push(()=>call(key, task, resolve, reject));
            }
          });
        });
      }
      else{
        toDo.push(()=>call(key, task, resolve, reject));
      }
    });
  })).then(()=>{
    done = true;
    callback(null, results);
  }).catch(e=>{
    done = true;
    callback(e, results);
  });

  while(run = toDo.shift()){
    run();
  }
}
export default autoTasks;

package.json

{
  "version": "0.1.0",
  "name": "0tis-autotasks",
  "main": "autoTasks.js"
}