A simple javascript library that executes given tasks in a queue.

Install

npm install --save shift.taskqueue

How it works

First you should instantiate a TaskQueue object. Then all it's left to do is push tasks to it. Note that tasks MUST ALWAYS be functions.

Pushed functions will be executed "first in first out" and they are never processed at the same time. Next function in line will be called only when the current one resolves (asynchronous) or returns (synchronous).

Pushed functions may or may not return a promise. If it does, task will be completed only when the promise resolves, calling then the next one in line.

Example

import TaskQueue from 'TaskQueue'; // const TaskQueue = require('TaskQueue');

let taskQueue = new TaskQueue();

taskQueue.push(func1).then(result => console.log(result));
taskQueue.push(func2).then(result => console.log(result));
taskQueue.push(func3).then(result => console.log(result));
taskQueue.push(func4).then(result => console.log(result));

setTimeout(() => {
    taskQueue.push(func2).then(result => console.log(result));
}, 1600);

setTimeout(() => {
    taskQueue.push(func3).then(result => console.log(result));
}, 5000);

function func1() {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve('func1 done processing');
        }, 1000);
    });
}

function func2() {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve('func2 done processing');
        }, 500);
    });
}

function func3() {
    return 'func3 done processing';
}

function func4() {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve('func4 done processing');
        }, 200);
    });
}

Output

*Approximate accumulated processing time from the beggining.

after 1000 milliseconds ---> 'func1 done processing'
after 1500 milliseconds ---> 'func2 done processing'
after 1500 milliseconds ---> 'func3 done processing'
after 1700 milliseconds ---> 'func4 done processing'
after 2100 milliseconds ---> 'func2 done processing'
after 5000 milliseconds ---> 'func3 done processing'