使用underscore.js在数组中提取对象

问题描述

我有一个n个对象的数组.我想每次拔出最后一个对象.例如，我在一个数组中有4个对象.我希望使用underscore.jS摘除第三个对象.每次我想要将最后一个对象从数组中拔出时.

Hi i had an array with n number of objects. I want to pluck the last but one object every-time. For example i had 4 objects in an array. I want the third object to be plucked using underscore.jS. Every time i want the last but one object to be plucked out of an array.

预先感谢

推荐答案

您确实不需要为此使用的库.

You really don't need a library for this.

var ary = ['thing1', 'thing2', 'thing3', 'thing4'];

var aryLength = ary.length;

var almostLast = ary[aryLength - 2];

这适用于任何数组，而不仅限于此示例ary.之所以有效，是因为数组是0索引的.在ary，ary[0] = 'thing1'，ary[1] = 'thing2'等中，因此数组中的最后一个东西的索引号比其长度小2.

This works for any array, not just this example ary. It works because arrays are 0-indexed. In ary, ary[0] = 'thing1', ary[1] = 'thing2', etc. So the last thing in an array is available at the index of two less than its length.

如果您需要使用下划线，我想您可以按以下方式使用_.last():

If you need to use underscore, I guess you can use _.last() as follows:

var lastTwo    = _.last(ary, 2),
    almostLast = lastTwo[0]; 

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