为什么此功能会变异数据? [英] Why does this function mutate data?

问题描述

function bubbleSort(toSort) {
  let sort = toSort;
  let swapped = true;
  while(swapped) {
    swapped = false;
    for(let i = 0; i < sort.length; i++) {
      if(sort[i-1] > sort[i]) {
        let temp = sort[i-1];
        sort[i-1] = sort[i];
        sort[i] = temp;
        swapped = true;
      }
    }
  }
  return sort;
}

let asdf = [1,4,3,2];
let asd = bubbleSort(asdf);

console.log(asdf, asd);

此代码的输出为:[1，2，3，4] [1，2，3，4].

The output to this code is: [ 1, 2, 3, 4 ] [ 1, 2, 3, 4 ].

我期望的是:         [1，4，3，2] [1，2，3，4].

What I would expect:         [ 1, 4, 3, 2 ] [ 1, 2, 3, 4 ].

我想知道的是为什么这会使asdf变量突变? bubbleSort函数采用给定的数组(asdf)，对其进行复制(排序)，然后处理该变量并将其返回，并将其asd设置为等于.我觉得自己是个白痴，但我不知道为什么这是:(

What I'm wondering, is why does this mutate the asdf variable? The bubbleSort function takes the given array (asdf), makes a copy of it (sort), and then deals with that variable and returns it, which asd is set equal to. I feel like an idiot but I have no clue why this is :(

推荐答案

bubbleSort函数采用给定的数组(asdf)，对其进行复制(排序)

The bubbleSort function takes the given array (asdf), makes a copy of it (sort)

不，不是.分配不会复制对象，它会创建对现有对象的另一个引用.

No, it doesn't. Assignment doesn't make a copy of an object, it creates another reference to an existing object.

复制数组的一种简单方法是使用 Array.prototype.slice :

A simple way to copy an array is to use Array.prototype.slice:

  let sort = toSort.slice( 0 );

有关一般复制对象的更多信息，请参见:如何正确进行克隆一个JavaScript对象?

For more on copying objects in general see: How do I correctly clone a JavaScript object?

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