如何在JavaScript中[1,2] + [4,5,6] [1] = 1,25 [英] How [1,2] + [4,5,6][1] = 1,25 in JavaScript

问题描述

我从访谈中得到了这个问题，

I got this question from Interview,

[1,2] + [4,5,6][1]

JavaScript给出答案 1,25 。

JavaScript giving answer 1,25.

是怎么回事？请清楚地解释。

How it's happening? Please explain clearly.

推荐答案

让我们从最后一部分开始，写得更详细

Lets start with the last part and write it more verbose

var arr   = [4,5,6];
var value = arr[1];

与

[4,5,6][1]

和数组从零开始，得出 5 ，所以我们确实有

and as arrays are zero based, that gives 5, so we really have

[1,2] + 5;

第一部分等于

[1,2].toString(),

返回字符串 1,2 ，因为在试图将表达式用于此类表达式时，该数组会转换为字符串，因为不能将数组添加到数字中，然后我们有

and that returns the string "1,2" because the array is converted to a string when trying to use it in an expression like that, as arrays can't be added to numbers, and then we have

"1,2" + 5

将字符串与数字连接会得到字符串，并将字符串加在一起得到

Concatenating strings with numbers gives strings, and adding the strings together we get

"1,25"

这篇关于如何在JavaScript中[1,2] + [4,5,6] [1] = 1,25的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！