在node.js中，初始程序被称为模块吗？

Question

When running the command line "node index.js", is index.js treated as a module with "module scope" for variables declared within it or is it global?

For example (in index.js):

a = 1;     // is "a" global?
var b = 1; // is "b" global?

I know subsequent modules brought in with "require" would have all their variable declarations declared with "var" stay within the module, but I'm not sure about the initially called js file (usually named index.js) since it's not brought in with "require" (unless node does this).

Answer 1

Node treats all script files as modules with their own " module " scope .

Node has a simple module loading system. In Node, files and modules are in one-to-one correspondence. [...]

The module created for the entry script will be assigned to require.main :

When a file is run directly from Node, require.main is set to its module . That means that you can determine whether a file has been run directly by testing

 require.main === module 

And, you can determined what's a global by using the in operator against the global object , which all globals become a property of:

a = 1;     // is "a" global?
var b = 1; // is "b" global?

console.log('a' in global); // true
console.log('b' in global); // false

Answer 2

The variables declared with the initial file are treated the same as all other files.

If you want to declare a variable as global, attach it to the GLOBAL property:

GLOBAL.a = 1;  // a should be available in all files

(the usual caveats about global variables apply here).