如何使用參數爲變量的函數？

Question

我一直在工作一個小項目來學習javascript的基礎知識，但我遇到了一個我無法修復的錯誤。我做了一些研究，但無濟於事。 我想要一個產生犯罪的程序（作爲笑話）。它從數組'people'中隨機選擇一個參數，並將其與陣列'進攻'中的一個相加。一切都很順利，直到我決定讓隨機函數變成一個函數。此時它開始做奇怪的事情，比如詢問朋友的名字後停下來，將personGenerator分配給'und​​efined'。 這裏是我的代碼：

<script> 
    //this is plonker base 

    //creates a variable that will start the game 
    var start = confirm("Are you sure want to participate in plonker base alpha?") 

    //starts and loops the game 
    if(start==true){ 
     //asks for another person's name 
     var person1 = prompt("Please name one of your best friends.") 
    } 

    //creates a randomizer function 
    var random = function (variable,subject){ 
     variable = subject[Math.floor(subject.length * Math.random())] 
    } 

    while(start==true){ 
     //creates array 'person' 
     var person = ["You are ","Your mum is ","Your dad is ", "The world is ", (person1 + " is ")] 
     var personGenerator 
     random(personGenerator,person) 

     //creates an array 'offence' 
     var offence = ["an idiot!", 
      "a complete pysco!!!", 
      "a smelly, worthless peice of junk!", 
      "a whale re-incarnated that looks like a squirrel!", 
      "a dumb pile of dirt that has the misfortune of seeing itself in the mirror once in a while!", 
      "a complete and utter plonker!", 
      "a dumbo!", 
      "a right dufus!!!", 
      "a pile of rabbit dung!", 
      "an intelligant, good looking king being... Did I mention - it's opposite day!", 
      "a bum-faced rat!!!", 
      "a fat, lazy oaf!", 
      "a blobfish look-alike!!!!!", 
      "a lump of toenail jelly!"] 
     var offenceGenerator = offence[Math.floor(offence.length * Math.random())] 
     //gives out the offence 
     alert(personGenerator + offenceGenerator) 
    } 
    { 
     alert("What a plonker!") 
    } 
</script> 

我是新來的JavaScript，所以我不很瞭解。請讓你的答案容易理解。如果我在任何時候使用了錯誤的術語，請說。

感謝， 里斯C.

Answer 1

這種結構並不在Javascript工作：

//creates a randomizer function 
var random = function (variable,subject){ 
    variable = subject[Math.floor(subject.length * Math.random())] 
} 

這不會改變變量的傳遞。相反，你應該從函數中返回新的隨機值。

//creates a randomizer function 
var random = function (subject){ 
    return subject[Math.floor(subject.length * Math.random())]; 
} 

而且，然後在您使用它：

var personGenerator = random(person); 

---

至於爲什麼你原來的代碼不Javascript中工作，這是因爲JavaScript並沒有通過在參考有真傳你可以改變原始變量指向的方式。當你這樣做：

//creates a randomizer function 
var random = function (variable,subject){ 
    variable = subject[Math.floor(subject.length * Math.random())] 
} 

random(personGenerator, person); 

在你的隨機函數包含爲您所做的函數調用時personGenerator變量的內容的variable說法。但是，它將是一個單獨的變量。所以，這樣做：

variable = subject[Math.floor(subject.length * Math.random())] 

只改變本地函數參數的值。它不會更改personGenerator的值。