uniqueue

only queue unique items and retrieve them only once

Installation

$ npm install --save uniqueue

Usage

'use strict';

const Uniqueue = require('uniqueue');

const { push, pop, remaining, queued, processed, clear } = new Uniqueue();

const urls = [
  'https://google.com',
  'https://google.com',
  'https://google.com/',
  'https://www.google.com'
];

// Only add unique items to the queue
urls.forEach(url => {
  push(url);
});
console.log('=>', queued.size, processed.size, remaining());
// => 3 0 3

// Extract items from queue
while (remaining() > 0) {
  console.log('=> remaining:', remaining());
  console.log('=>', pop());
  console.log('=> processed:', processed.size);
  console.log();
}
// => remaining: 3
// => https://google.com
// => processed: 1
//
// => remaining: 2
// => https://google.com/
// => processed: 2
//
// => remaining: 1
// => https://www.google.com
// => processed: 3

// Clear the queue
clear();
console.log('=>', queued.size, processed.size, remaining());
// => 0 0 0

// Use a custom matcher function to prevent similar duplicates
const matcher = (a, b) => {
  return (
    a.replace(/[^a-z]/gi, '') === b.replace(/[^a-z]/gi, '') ||
    a.replace(/:\/\/www\./i, '://') === b.replace(/:\/\/www\./i, '://')
  );
};
urls.forEach(url => {
  push(url, matcher);
});
console.log('=>', [...queued]);
// => [ 'https://google.com' ]

// * Use a custom matcher function during initialization
const queue = new Uniqueue(matcher);
// ...

API

Uniqueue([matcher])

Returns a new queue instance.

• matcher

  • Optional : Function is evaluated on every attempt to add an item to the queue.

    • Overrides the default Set value equality check

    • e.g. (a, b) => a.name.toUpperCase() === b.name.toUpperCase() will prevent { name: "Bob" } from being added if { name: "BOB" } is already in the queue.

queue

Uniqueue instance.

• .push(item [, matcher])

  Adds an item of Any type to the queue.

  • matcher

    Optional : Function overrides the matcher function provided during initialization (if it was provided).

• .pop()

  Returns the next available item from the queue or null if no items are available.

• .remaining()

  Returns the Number of available items from the queue.

• .queued

  The Set holding all unique items added to the queue.

• .processed

  The Set holding all items that have been pop()'d from the queue.

• .clear()

  Clears the queue, including .queued and .processed.

License

ISC © Buster Collings