Find items in a collection

find.js

// Find items in a collection

var _ = module.exports = {}

_.find          = function(c, s){ return search(c, s, {one:true}) }
_.findIndex     = function(c, s){ return search(c, s, {one:true, index:true}) }
_.findLast      = function(c, s){ return search(c, s, {one:true, last:true}) }
_.findLastIndex = function(c, s){ return search(c, s, {one:true, index:true, last:true}) }
_.filter        = function(c, s){ return search(c, s) }


function search(collection, search, opt){
  opt = opt || {}

  function matchProps(item){
    return Object.keys(search).every(function(k){
      return item[k] === search[k]
    })
  }

  var test = typeof search === 'function' ? search : matchProps
  var isArray = typeof collection.length === 'number'
  var keys = Object.keys(collection)
  var results = []
  var start = 0
  var end = keys.length - 1

  // Iterate
  for(var i = start; i <= end; i++){

    // Reverse
    var ix = opt.last ? end - i : i

    // Get key & item
    var key = keys[ix]
    if(isArray) key = +key
    var item = collection[key]

    // Test and return or collect results
    if(test(item, key)){
      var res = opt.index ? key : item
      if(opt.one) return res
      results.push(res)
    }
  }

  if(!opt.one) return results
}



/////////////////////////////////////////////////
//// Tests
/*

;(function test(){
  
  var arr = [  {i:0, v:1},   {i:1, v:0},   {i:2, v:0},   {i:3, v:1}]
  var obj = {a:{i:0, v:1}, b:{i:1, v:0}, c:{i:2, v:0}, d:{i:3, v:1}}
  
  var test = suite()

  test(       _.filter(arr, {v:0}), [{i:1, v:0}, {i:2, v:0}])
  test(         _.find(arr, {v:0}), {i:1, v:0})
  test(     _.findLast(arr, {v:0}), {i:2, v:0})
  test(    _.findIndex(arr, {v:0}), 1)
  test(_.findLastIndex(arr, {v:0}), 2)
  
  test(       _.filter(arr, {v:1}), [{i:0, v:1}, {i:3, v:1}])
  test(         _.find(arr, {v:1}), {i:0, v:1})
  test(     _.findLast(arr, {v:1}), {i:3, v:1})
  test(    _.findIndex(arr, {v:1}), 0)
  test(_.findLastIndex(arr, {v:1}), 3)

  test(       _.filter(obj, {v:1}), [{i:0, v:1}, {i:3, v:1}])
  test(         _.find(obj, {v:1}), {i:0, v:1})
  test(     _.findLast(obj, {v:1}), {i:3, v:1})
  test(    _.findIndex(obj, {v:1}), 'a')
  test(_.findLastIndex(obj, {v:1}), 'd')

  test.end()

})()


function suite(){
  var line = Array(10).join('-')
  console.log(line, 'TEST:', line)
  var fail

  var test = function(a, b){
    a = JSON.stringify(a)
    b = JSON.stringify(b)
    var ok = a === b
    var v = [ok ? 'OK' : 'FAIL', a, b]
    console[ok ? 'log' : 'error'](v.join(' -- '))
    if(!ok) fail = true
  }

  test.end = function(){
    fail ? console.error(line, 'DANG.', line)
         :   console.log(line, 'YEAH!', line)
  }

  return test
}

*/