javascript 如何从数组中删除除最后 N 个元素之外的所有元素？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/18277603/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How can I remove all but the last N elements from an array?
提问by titans
I have an array. I have a variable that shows how many elements in the array must be left at the end. Is there a function that would do that? Example:
我有一个数组。我有一个变量，显示数组中最后必须保留多少个元素。有没有一个功能可以做到这一点？例子：
var arr = [1, 2, 3, 4, 5];
var n = 2;
arr = someFunction(n); // arr = [4, 5];
I want an array with the last nelements in it.
我想要一个包含最后一个n元素的数组。
回答by Craig
The slice method is what you want. It returns a new object, so you must replace your existing object with the new one.
slice 方法就是你想要的。它返回一个新对象，因此您必须用新对象替换现有对象。
arr = arr.slice(-1 * n);
Alternatively, modify the existing array with splice().
或者，使用splice().
arr.splice(0, arr.length - n);
Splice is the more efficient, since it is not copying elements.
Splice 效率更高，因为它不复制元素。
