为何或如何这是否证明了JavaScript数组的平等？ [英] Why or how does this prove JavaScript array equality?

问题描述

在这个答案有一个简单的函数，将返回包含原始值数组的数组平等。

In this answer there is a simple function that will return array equality for arrays that contain primitive values.

不过，我不知道为什么它的工作原理。下面是函数：

However, I'm not sure why it works. Here is the function:

function arrays_equal(a,b) { return !!a && !!b && !(a<b || b<a); }

我在下半场最感兴趣;该位：

I'm mostly interested in the second half; this bit:

!(a<b || b<a)

为什么在＆LT; 和＆GT; 工作比较阵列但当 == 不？

Why does the < and > work when comparing the arrays but the == doesn't?

如何做的比超过方法中的JavaScript的工作更少，更大？

How do the less than and greater than methods work within JavaScript?

推荐答案

通过＆LT; / ＆GT; ，阵列被转换为字符串第一，因此没有提供检查平等的可靠方法。

With </>, the arrays are converted to strings first, and as such do not provide a reliable method of checking equality.

== ，因为对象是通过引用检查不工作：

== does not work because objects are checked by reference:

[] == []; // false, two separate objects

var a = [];
a == a; // true, refer to the same object

的＆LT; / ＆GT; 招是有缺陷的：

The </> trick is flawed:

var a = [1, [2, 3]],
    b = [[1, 2], 3];

!(a<b || b<a); // true

该计算结果为真正，因为它们都转换成字符串1,2,3前它们会被检出（＆LT; / ＆GT; 做的对象而不是直接的工作）。

This evaluates to true, because they are both converted to the string "1,2,3" before they are checked (</> do not "directly" work for objects).

所以基本上，你是比较字符串的平等。对于字符串， A == b 确实是一样的（A＆LT; b || B＆LT; A）！ - ＆LT; / ＆GT; 字符串检查字符codeS，所以两个相等的字符串既不是小，也不大，因为这不是在字符串的任何字符code的情况。

So basically, you are comparing equality of the strings. For strings, a == b is indeed the same as !(a<b || b<a) - </> for strings check character codes, so two equal strings are neither "smaller" nor "greater" because that's not the case for any character code in the strings.

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