freeCodeCamp/guide/chinese/certifications/javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions/index.md

title	localeTitle
Refactor Global Variables Out of Functions	重构函数的全局变量

重构函数的全局变量

• 如果您在更改bookList时遇到问题，请尝试在函数中使用该数组的副本。

• 这里有一些关于[JavaScript如何处理函数参数]的更多信息（https://codeburst.io/javascript-passing-by-value-vs- reference-explanation-in-plain-english-8d00fd06a47c）。

基本代码解决方案

解决方案1

function add (arr, bookName) { 
  let newArr = [...arr];  // Copy the bookList array to a new array. 
  newArr.push(bookName);  // Add bookName parameter to the end of the new array. 
  return newArr; // Return the new array. 
 } 
 
 function remove (arr, bookName) { 
  let newArr = [...arr];  // Copy the bookList array to a new array. 
  if (newArr.indexOf(bookName) >= 0) {   // Check whether the bookName parameter is in new array. 
    /. 
    newArr.splice(newArr.indexOf(bookName), 1); // Remove the given paramater from the new array. 
    return newArr; // Return the new array. 
    } 
 } 

解决方案2

function add (list,bookName) { 
  return [...list, bookName]; 
 } 
 
 function remove (list,bookName) { 
  if (list.indexOf(bookName) >= 0) { 
    return list.filter((item) => item !== bookName); 
    } 
 }