Node.JS全局变量声明本地名称是否相同

Question

I have this code:

let manager;
exports.setup = async manager => {
    this.manager = manager;
};

This is possible duplicate but every time I saw this, solution was to use window.manager = manager to set global variable from inside function. How to do this in Node.JS where is no window ? this.manager not working, because its seems this.manager !== manager (the global one)

Answer 1

Your function parameter hides the local variable in this case.

Consider the following 2 modules:

lib.js

let manager = 2;
exports.setup = async manager => {
    this.manager = manager;
};

main.js

var v = require("./lib.js");
v.setup(5);
console.log(v.manager);

This prints 5 because manager is the parameter you pass to the function. If you want to obtain the value of the local manager ( 2 in this example) you need to change the name of the function parameter or remove it entirely.

let manager = 2;
exports.setup = async input => {
    this.manager = manager;
};

or

let manager = 2;
exports.setup = async () => {
    this.manager = manager;
};