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?
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 itsthis
value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method. Whether theslice
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.
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