为什么数组切片将javascript参数转换为数组

2022-01-21 00:00:00 arrays slice arguments javascript

为什么将切片方法应用于javascript arguments 值如下Array.prototype.slice.call(arguments) 将其转换为数组?如果在数组上使用 slice，并且 arguments 不是数组，那么它是如何工作的?将 slice 应用于参数是否只是一种特殊情况?

Why does applying the slice method to the javascript arguments value as follows Array.prototype.slice.call(arguments) convert it to an array? If slice is used on arrays, and arguments is not an array, then how does this work? Is it just a special case when slice is applied to arguments?

推荐答案

来自 EcmaScript 规范Array.prototype.slice:

注意 slice 函数是故意通用的；它不要求其 this 值是 Array 对象.因此，它可以转移到其他类型的对象中用作方法.slice 函数能否成功应用于宿主对象取决于实现.

NOTE The slice function is intentionally generic; it does not require that its this value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method. Whether the slice function can be applied successfully to a host object is implementation-dependent.

因此，slice 适用于每个具有 length 属性的对象(如 Arguments 对象).即使对于那些不这样做的人，它也只会返回一个空数组.

And so, slice works on every object that has a length property (like Arguments objects). And even for those that do not, it then just returns an empty array.

相关文章