RangeError：array.push(...) 超出了最大调用堆栈大小

Question

下面的简单代码产生RangeError: Maximum call stack size exceeded

const arr = []
for (let i = 0; i < 135000; i++) {
    arr.push(i)
}
const arr2 = []
// something else here that changes arr2
arr2.push(...arr)

1) 为什么会这样？ （我只是将元素添加到数组中，为什么会增加堆栈大小？）

2) 如何解决这个错误？ （我的目标是在 arr2 中创建 arr 的浅拷贝）

Answer 1

那里的传播运算符pushes all elements in the original array into the stack, just like .apply:

const arr = [];

for (let i = 0; i < 10; i++) {
  arr.push(i);
}

const arr2 = [];

// Something else here that changes arr2:
arr2.push(0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

Array.prototype.push.apply(arr2, arr);

console.log(arr2.join(', '));

因此，在这两种情况下您可以处理的数据量都受到堆栈大小的限制：

const arr = [];

for (let i = 0; i < 135000; i++) {
  arr.push(i);
}

const arr2 = [];

// Something else here that changes arr2:
arr2.push(0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

Array.prototype.push.apply(arr2, arr);

console.log(arr.length, arr2.length);

你可以这样做：

const arr = [];

for (let i = 0; i < 135000; i++) {
  arr.push(i);
}

let arr2 = [];

// Something else here that changes arr2:
arr2.push(0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

arr2 = [...arr2, ...arr];

console.log(arr.length, arr2.length);

Answer 2

//I hope this will help you to make shallow copy of arr into arr2

let arr = []
for (let i = 0; i < 135000; i++) {
    arr.push(i)
}
let arr2 = []
// something else here that changes arr2
arr2=arr

console.log(arr2[0],arr[0]);
//Both 0,0
arr[0]=100

console.log(arr[0],arr2[0])

//Both 100,100