在Node.js中，为什么使用require函数的模块之间的变量相等？

Question

I have the following files in the same directory:

data.js

var anArray = [1,2];
module.exports = anArray;

mod1.js

var data = require('./data');
module.exports = data;

mod2.js

var data = require('./data');
module.exports = data;

main.js

var mod1 = require('./mod1');
var mod2 = require('./mod2');

When I do mod1 === mod2 it is true Why is that? My initial belief was that mod1 and mod2 files should contain an array but that are different (different references to the array objects).

Answer 1

This is because modules are cached. Since you're referencing the same module twice, the second one is returning the exact same as the first. In your example, it's the same as doing the following:

const arr1 = [1,2]
const arr2 = [1,2]

arr1 === arr1 // true
arr1 === arr2 // false

The last line is false because you're comparing two different arrays.