javascript - 函数应该是非破坏性的，但它正在修改我的变量

Question

我有以下代码，它设置 special 来运行函数 convertSpecial，该函数将用提供的字符替换 array1 中的撇号。在本例中，是一个空格。由于替换字符是空格，因此它将将该元素拆分为两个，然后展平数组。然后，它将检查 special 中的任何元素是否与 array2 中的任何元素匹配。这将返回 false。然后它将用根本不包含字符的撇号替换并重新检查 array2。

convertSpecial 和变量 special 背后的想法是它应该对 array1 非破坏性，但这并没有发生，因为你可以看到:

var array1 = ["o'hara"];
var array2 = ["ohara"];
var special = '';

function convertSpecial(a,b,c) {
	var aCopy = a;
	for (let i = 0; i < aCopy.length; i++) {
		if (aCopy[i].includes(b)) {
			if (c == '') {							
				aCopy[i] = aCopy[i].replace(b,c);
			} else {
				aCopy[i] = aCopy[i].replace(b,c).split(' ');
						
				aCopy = aCopy.flat();
			}
		}				
	}
			
	return aCopy;
}
  
console.log('array1 1 = '+array1); // returns array1 1 = o'hara as expected

special = convertSpecial(array1,"'"," ");
				
console.log('array1 2 = '+array1); // returns array1 2 = o,hara THIS SHOULD NOT HAVE BEEN MODIFIED
console.log('special 1 = '+special); //returns special 2 = o,hara as expected

if (array2.some(v => special.includes(v)) == true) {
console.log('array1 3 = '+array1); // ignored as expected

array1 = specialDECln;
} else {
console.log('array1 4 = '+array1); //returns array1 4 = o,hara  THIS SHOULD NOT HAVE BEEN MODIFIED

special = convertSpecial(array1,"'","");
		
console.log('array1 5 = '+array1); //returns array1 5 = o,hara THIS SHOULD NOT HAVE BEEN MODIFIED
console.log('special 2= '+special); //returns special 2 = o,hara should be ohara
					
if (array2.some(v => special.includes(v)) == true) {
	array1 = special;
} 
}
      
console.log(array2 == special);   //returns false, should be true because expected ohara = ohara

一切都按其应有的方式运行，除了 array1 在根本不应该被修改的情况下被修改。由于它被修改，special 被设置为不正确的值。

我做错了什么以及如何解决它？

Answer 1

您需要克隆该数组以避免突变。有很多方法可以做到这一点，另一种方法是使用 Spread 语法，如下所示:

let result = [...a]; // This creates a new array with the index-values from array a.

var array1 = ["o'hara"];
var special = ''

console.log("array1 = " + array1); // returns array1 = o'hara as expected

function convertSpecial(a, b, c) { // a = array, b = character to replace, c = character to replace with
  let result = [...a];
  for (let i = 0; i < result.length; i++) {
    if (result[i].includes(b)) {
      if (c == '') {
        result[i] = result[i].replace(b, c);
      } else {
        result[i] = result[i].replace(b, c).split(' ');
        result = result.flat();
      }
    }
  }

  return result;
}

special = convertSpecial(array1, "'", " ");

console.log("array1 = " + array1); // returns array1 = o, hara but it should be o'hara

console.log("special = " + special); // returns special = o, hara as expected