Node.js模块中的功能

Question

I can define a module in node.js:
mymodule.js

exports.bar = "Hello";
exports.foo = function(){
    console.log(exports.bar);
}

I can require the module:
app.js

var baz = require("./mymodule.js");
baz.foo(); //Logs "Hello" in the console

If I call the foo function as above, it logs "Hello" in the console. However, the variable that foo is logging is exports.bar , not baz.bar . Does Node.js automatically know to switch them or the exports object still exists?

Answer 1

exports is a special object which is included in every JS file in the Node.js application by default.

So anything you export in a file ( mymodule.js in your case) is a property on this object and when you require this module export object is assigned to the requiring object ( baz in your case).

When you do

var baz = require("./mymodule.js");

Your baz variable now looks like something

baz = {
    bar : "Hello",
    foo : () => {
        console.log(baz.bar)
     }
}

And when you call baz.foo() you see "Hello" printed

Answer 2

当您在模块中使用导出时，这将为对象添加属性，并将其像本地对象（变量）一样使用。