提示參數(shù)

問題

你的函數(shù)將會被可變數(shù)量的參數(shù)所調(diào)用。

解決方案

使用splat 。

loadTruck = (firstDibs, secondDibs, tooSlow...) ->
    truck:
        driversSeat: firstDibs
        passengerSeat: secondDibs
        trunkBed: tooSlow

loadTruck("Amanda", "Joel")
# => { truck: { driversSeat: "Amanda", passengerSeat: "Joel", trunkBed: [] } }

loadTruck("Amanda", "Joel", "Bob", "Mary", "Phillip")
# => { truck: { driversSeat: "Amanda", passengerSeat: "Joel", trunkBed: ["Bob", "Mary", "Phillip"] } }

使用尾部參數(shù)：

loadTruck = (firstDibs, secondDibs, tooSlow..., leftAtHome) ->
    truck:
        driversSeat: firstDibs
        passengerSeat: secondDibs
        trunkBed: tooSlow
    taxi:
        passengerSeat: leftAtHome

loadTruck("Amanda", "Joel", "Bob", "Mary", "Phillip", "Austin")
# => { truck: { driversSeat: 'Amanda', passengerSeat: 'Joel', trunkBed: [ 'Bob', 'Mary', 'Phillip' ] }, taxi: { passengerSeat: 'Austin' } }

loadTruck("Amanda")
# => { truck: { driversSeat: "Amanda", passengerSeat: undefined, trunkBed: [] }, taxi: undefined }

討論

通過在函數(shù)其中的（不多于）一個參數(shù)之后添加一個省略號（...），CoffeeScript能把所有不被其他命名參數(shù)采用的參數(shù)值整合進一個列表中。就算并沒有提供命名參數(shù)，它也會制造一個空列表。