blackjack-strategy
Version:
provides a suggested action for a player based on Basic Strategy
253 lines (234 loc) • 9.85 kB
JavaScript
/*
* MIT License
* Copyright (c) 2016 Garrett Vargas
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
module.exports = {
// Recommended actions follow simple guidelines:
// * always split aces and eights
// * double 9 and 10 vs. dealer low card, and double 11 always
// * hit on a soft 17 or less, stand on a soft 18 or more
// * stand on any hand 12+ on a dealer low card (never bust)
// * on a dealer high card, hit until 17+ (mimic the dealer)
SuperEasyStrategy: function(playerCards, dealerCard, handValue, handCount, dealerCheckedBlackjack, options)
{
// Can you split?
if ((playerCards[0] == playerCards[1]) && (playerCards.length == 2) && (handCount < options.maxSplitHands))
{
// only split As and 8s
if ((playerCards[0] == 1) || (playerCards[0] == 8))
{
return "split";
}
}
// Double
if (((playerCards.length == 2) && ((handCount == 1) || options.doubleAfterSplit)) &&
((handValue.total >= options.doubleRange[0]) && (handValue.total <= options.doubleRange[1])))
{
// Only on 9-10 against a dealer low card
if ((handValue.total == 9) && (dealerCard < 7) && (dealerCard != 1))
{
return "double";
}
if ((handValue.total == 10) && (dealerCard < 7) && (dealerCard != 1))
{
return "double";
}
if (handValue.total == 11)
{
return "double";
}
}
// Hit and stand
if (handValue.soft)
{
// Hit on a soft 17 or less, stand on a soft 18 or more
return (handValue.total < 18) ? "hit" : "stand";
}
// On a dealer low card, stand on any hand 12+ (never bust)
if (handValue.total <= 11)
{
return "hit";
}
else if ((dealerCard < 7) && (dealerCard != 1))
{
return "stand";
}
else
{
// On a dealer high card, hit until 17+ (mimic the dealer)
// Hit on 7 or above, else stand
return (handValue.total < 17) ? "hit" : "stand";
}
},
// Recommended actions follow super-easy strategy, plus:
// * Split 2s, 3s, 6s, 7s, and 9s vs. a dealer low card
// * Double on 10 vs. a dealer 7, 8, or 9 (in addition to dealer 2 through 6)
// * Double A6, A7 vs. a dealer low card
SimpleStrategy: function(playerCards, dealerCard, handValue, handCount, dealerCheckedBlackjack, options)
{
// If early surrender is allowed, check that now (that's what early surrender means - before dealer checks for blackjack
if ((options.surrender == "early") && (!handValue.soft && (handValue.total == 16) && (dealerCard == 10)))
{
return "surrender";
}
// Can you split?
if ((playerCards[0] == playerCards[1]) && (playerCards.length == 2) && (handCount < options.maxSplitHands))
{
// Always split As and 8s
if ((playerCards[0] == 1) || (playerCards[0] == 8))
{
return "split";
}
// Split unless 4s, 5s, and 10s against a dealer low card
if ((playerCards[0] != 4) && (playerCards[0] != 5) && (playerCards[0] != 10) && (dealerCard < 7) && (dealerCard != 1))
{
return "split";
}
}
// Double
if (((playerCards.length == 2) && ((handCount == 1) || options.doubleAfterSplit)) &&
((handValue.total >= options.doubleRange[0]) && (handValue.total <= options.doubleRange[1])))
{
// Only on 9 against a dealer low card
if ((handValue.total == 9) && (dealerCard < 7) && (dealerCard != 1))
{
return "double";
}
// Double on 10 vs. a dealer 7, 8, or 9 (in addition to dealer 2 through 6)
if ((handValue.total == 10) && (dealerCard < 10) && (dealerCard != 1))
{
return "double";
}
// Double A6, A7 vs. a dealer low card
if (playerCards.includes(1) && (playerCards.includes(6) || playerCards.includes(7)) && (dealerCard < 7) && (dealerCard != 1)) {
return "double";
}
if (handValue.total == 11)
{
return "double";
}
}
// Hit and stand
if (handValue.soft)
{
// Hit on a soft 17 or less, stand on a soft 18 or more
return (handValue.total < 18) ? "hit" : "stand";
}
// On a dealer low card, stand on any hand 12+ (never bust)
if (handValue.total <= 11)
{
return "hit";
}
else if ((dealerCard < 7) && (dealerCard != 1))
{
return "stand";
}
else
{
// On a dealer high card, hit until 17+ (mimic the dealer)
// Hit on 7 or above, else stand
return (handValue.total < 17) ? "hit" : "stand";
}
},
// Recommended actions follow super-easy and simple strategy, plus:
// * Double A2-A5 vs. a dealer 5,6
// * Stand on soft 18 or more Exception: Hit S18 vs 9, 10, Ace
// * Dealer low card: Never Bust Stand on 12 or more Exception: Hit 12 vs 2, 3
GreatStrategy: function(playerCards, dealerCard, handValue, handCount, dealerCheckedBlackjack, options)
{
// If early surrender is allowed, check that now (that's what early surrender means - before dealer checks for blackjack
if ((options.surrender == "early") && (!handValue.soft && (handValue.total == 16) && (dealerCard == 10)))
{
return "surrender";
}
// Can you split?
if ((playerCards[0] == playerCards[1]) && (playerCards.length == 2) && (handCount < options.maxSplitHands))
{
// Always split As and 8s
if ((playerCards[0] == 1) || (playerCards[0] == 8))
{
return "split";
}
// Split unless 4s, 5s, and 10s against a dealer low card
if ((playerCards[0] != 4) && (playerCards[0] != 5) && (playerCards[0] != 10) && (dealerCard < 7) && (dealerCard != 1))
{
return "split";
}
}
// Double
if (((playerCards.length == 2) && ((handCount == 1) || options.doubleAfterSplit)) &&
((handValue.total >= options.doubleRange[0]) && (handValue.total <= options.doubleRange[1])))
{
// Only on 9 against a dealer low card
if ((handValue.total == 9) && (dealerCard < 7) && (dealerCard != 1))
{
return "double";
}
// Double on 10 vs. a dealer 7, 8, or 9 (in addition to dealer 2 through 6)
if ((handValue.total == 10) && (dealerCard < 10) && (dealerCard != 1))
{
return "double";
}
if (playerCards.includes(1)) {
// Double A6, A7 vs. a dealer low card
if ((playerCards.includes(6) || playerCards.includes(7)) && (dealerCard < 7) && (dealerCard != 1)) {
return "double";
}
// Double A2-A5 vs. a dealer 5,6
if ((playerCards.includes(2) || playerCards.includes(3) || playerCards.includes(4) || playerCards.includes(5)) && ((dealerCard == 5) || (dealerCard == 6))) {
return "double";
}
}
if (handValue.total == 11)
{
return "double";
}
}
// Hit and stand
if (handValue.soft)
{
// Hit on a soft 17 or less
if (handValue.total < 18)
{
return "hit";
}
// Stand on soft 18 or more
// Exception: Hit S18 vs 9, 10, Ace
return (handValue.total == 18 && ((dealerCard > 8) || (dealerCard == 1))) ? "hit" : "stand";
}
// On a dealer low card, stand on any hand 12+ (never bust)
// Exception: Hit 12 vs 2, 3
if (handValue.total <= 11)
{
return "hit";
}
else if ((handValue.total == 12) && ((dealerCard == 2) || (dealerCard == 3))) {
return "hit";
}
else if ((dealerCard < 7) && (dealerCard != 1))
{
return "stand";
}
else
{
// On a dealer high card, hit until 17+ (mimic the dealer)
// Hit on 7 or above, else stand
return (handValue.total < 17) ? "hit" : "stand";
}
}
};