compare.js

Comparator functions for your favorite sort-algo

Installation

npm install compare.js

Usage

var mergesort = require('divide-et-impera');
var compare = require('compare.js');
var desc = compare.desc;
var caseInsensitive = compare.caseInsensitive;
// or require only what you need
var desc = require('compare.js/desc');
var caseInsensitive = require('compare.js/caseInsensitive');


// Basic usage
mergesort([3, 1, 2, 4, 2], desc()); // => [4, 3, 2, 2, 1]
mergesort(['a', 'c', 'C', 'B', 'b'], caseInsensitive()); // => ['a', 'B', 'b', 'c', 'C']
mergesort(['a', 'c', 'C', 'B', 'b'], desc(caseInsensitive())); // => ['B', 'b', 'c', 'C', 'a']
mergesort(['a', 'c', 'C', 'B', 'b'], desc(caseInsensitive())); // => ['B', 'b', 'c', 'C', 'a']

// Compose a sort function
var compose = require('compose-function');
var curry = require('chickencurry');

var sortDescByName = curry(mergesort)
  (curry.__, compose(
      caseInsensitive,
      curry(property)('name'),
      desc
    )()
  ); 

var users = [{
  name: 'Bylexus'
}, {
  name: 'Ai-Linh'
}, {
  name: 'Schtoeffel'
}];

sortDescByName(users); 
/* => [{
  name: 'Schtoeffel'
}, {
  name: 'Bylexus'
}, {
  name: 'Ai-Linh'
}]

API

simple() => comparator(a,b)

Simply checks if a is smaller then b

simple()(1, 2); // => -1
simple()(1, 1); // => 0
simple()(2, 1); // => 1

mergesort(list, simple());

date() => comparator(a,b)

Checks dates using moment.js.

date()(new Date('2015', '02', '1'), new Date('2015', '01', '31')); // => -1
date()(new Date('2015', '02', '1'), new Date('2015', '02', '1')); // => 0
date()(new Date('2015', '01', '31'), new Date('2015', '02', '1')); // => 1

date('DD.MM.YYYY')('18.01.1986', '19.01.1986'); // => -1
date('DD.MM.YYYY')('18.01.1986', '18.01.1986'); // => 0
date('DD.MM.YYYY')('18.01.1986', '17.01.1986'); // => 1

mergesort(list, date('DD.MM.YYYY'));

desc([comparator=simple]) => comparator(a,b)

Inverts a comparator.

desc(simple())(1, 2); // => 1
desc(simple())(1, 1); // => 0
desc(simple())(2, 1); // => -1

mergesort(list, desc(date()));

property(propertyName, [comparator=simple]) => comparator(a,b)

Compares a property of two objects.

var foo = {
  name: 'foo'
};
var bar = {
  name: 'bar'
};

property('name')(foo, bar); // => 1
property('name')(foo, foo); // => 0
property('name')(bar, foo); // => -1

// this works
property('name', caseInsensitive())
// this doesn't
caseInsensitive(property('name'))

mergesort(list, property('name'));

caseInsensitive([comparator=simple]) => comparator(a,b)

Compares a property of two objects.

caseInsensitive()('a', 'A'); // => 0
caseInsensitive()('A', 'a'); // => 0

mergesort(list, property('name', caseInsensitive()));