✨ chain of responsibility

Author: tangweikun

src/behavioral/chain of responsibility/Sample-3.js

@@ -0,0 +1,76 @@
+var MoneyStack = function(billSize) {
+  this.billSize = billSize
+  this.next = null
+}
+
+MoneyStack.prototype = {
+  withdraw: function(amount) {
+    var numOfBills = Math.floor(amount / this.billSize)
+    if (numOfBills > 0) {
+      this._ejectMoney(numOfBills) // Eject the bills
+      amount = amount - this.billSize * numOfBills // Shrink the amount by how much money we ejected
+    }
+    // If there is any money left to withdraw and if we have
+    // another stack in the line, pass the request on
+    amount > 0 && this.next && this.next.withdraw(amount)
+  },
+
+  // set the stack that comes next in the chain
+  setNextStack: function(stack) {
+    this.next = stack
+  },
+
+  // private method that ejects the money
+  _ejectMoney: function(numOfBills) {
+    console.log(
+      numOfBills + ' $' + this.billSize + ' bill(s) has/have been spit out',
+    )
+  },
+}
+
+var ATM = function() {
+  // Create the stacks of money
+  // We'll show you the implementation for this next
+  var stack100 = new MoneyStack(100)
+  var stack50 = new MoneyStack(50)
+  var stack20 = new MoneyStack(20)
+  var stack10 = new MoneyStack(10)
+  var stack5 = new MoneyStack(5)
+  var stack1 = new MoneyStack(1)
+
+  // Set the hierarchy for the stacks
+  stack100.setNextStack(stack50)
+  stack50.setNextStack(stack20)
+  stack20.setNextStack(stack10)
+  stack10.setNextStack(stack5)
+  stack5.setNextStack(stack1)
+
+  // Set the top stack as a property
+  this.moneyStacks = stack100
+}
+
+ATM.prototype.withdraw = function(amount) {
+  this.moneyStacks.withdraw(amount)
+}
+
+// USAGE
+var atm = new ATM()
+
+console.log('===186===')
+atm.withdraw(186)
+/* outputs:
+  1 $100 bill(s) has/have been spit out
+  1 $50 bill(s) has/have been spit out
+  1 $20 bill(s) has/have been spit out
+  1 $10 bill(s) has/have been spit out
+  1 $5 bill(s) has/have been spit out
+  1 $1 bill(s) has/have been spit out
+*/
+
+console.log('===72===')
+atm.withdraw(72)
+/* outputs:
+  1 $50 bill(s) has/have been spit out
+  1 $20 bill(s) has/have been spit out
+  2 $1 bill(s) has/have been spit out
+*/