是否可以在 javascript 中创建一个固定长度的数组? [英] Is it possible to create a fixed length array in javascript?

问题描述

是否可以在 Javascript 中创建一个长度保证保持不变的数组?

Is it possible, in Javascript, to create an array whose length is guaranteed to remain the same?

例如，创建长度为 2 的数组 A.随后，任何尝试调用 A.push() 或 A.pop()，或者设置A[5]的值都会失败.A.length 永远是 2.

For example, the array A is created with length 2. Subsequently, any attempt to call A.push() or A.pop(), or set the value of A[5] will fail. A.length will always be 2.

这是类型化数组(例如Float32Array)的工作方式.它们有固定的尺寸.但我想要一种在常规数组上获得相同行为的方法.

This is the way that typed arrays (eg Float32Array) already work. They have fixed size. But I want a way to get the same behaviour on a regular Array.

对于我的具体情况，我想创建一个固定长度的数组，其中每个条目都是一个对象.但我还是想知道一般问题的答案.

For my specific situation, I would like to create a fixed-length array where each entry is an object. But I would still like to know the answer to the general question.

推荐答案

更新:

Object.seal (这是 ES2015 的一部分)将做到这一点:

Object.seal (which is part of ES2015) will do just that:

// create array with 42 empty slots
let a = new Array(42);

if(Object.seal) {
  // fill array with some value because
  // empty slots can not be changed after calling Object.seal
  a.fill(undefined);

  Object.seal(a);
  // now a is a fixed-size array with mutable entries
}

原答案:

差不多.正如 titusfx 所建议的那样，您可以冻结对象:

Almost. As was suggested by titusfx you can freeze the object:

let a = new Array(2);

// set values, e.g.
a[0] = { b: 0; }
a[1] = 0;

Object.freeze(a);

a.push(); // error
a.pop(); // error
a[1] = 42; // will be ignored
a[0].b = 42; // still works

但是，您无法更改冻结对象的值.如果您有一组对象，这可能不是问题，因为您仍然可以更改对象的值.

However you are unable to change the values of a freezed object. If you have an array of objects this may not be a problem since you can still change the values of the objects.

对于数字数组，当然有类型化数组.

For arrays of numbers there are of course typed arrays.

Object.freeze 是 ES2015 但大多数浏览器似乎都支持它，包括 IE9.您当然可以对其进行功能测试:

Object.freeze is part of ES2015 but most browsers seem to support it, including IE9. You could of course feature-test it:

if(Object.freeze) { Object.freeze(obj);}

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