Node.js has a very clever design for module path resolution and code loading. Most languages punt when asked to load two modules depending on different versions of a shared third module, but not Node. This presentation depicts a handful of module loading scenarios by demonstrating the filesystem layout for each.

1. Altamira
Node.js Module
Resolution
Jeff Kunkle
April 19, 2012

2. Path Resolution

3. require(“./mymodule.js”);
1

4. mymodule.js
/projects/preso/
main.js
require(“./mymodule.js”);

5. require(“./mymodule”);
2

6. /projects/preso/
main.js
require(“./mymodule”);

7. mymodule.js
/projects/preso/
main.js
require(“./mymodule”);

8. mymodule.js
/projects/preso/
mymodule.json
main.js
require(“./mymodule”);

9. mymodule.js
/projects/preso/
mymodule.json
mymodule.node
main.js
require(“./mymodule”);

10. require(“./mymodule”);
/projects/preso/
main.js
mymodule/
package.json
init.js

11. require(“./mymodule”);
mymodule/
/projects/preso/
index.js
main.js

12. require(“./mymodule”);
mymodule/
/projects/preso/
index.node
main.js

13. require(“mymodule”);
3

14. require(“mymodule”);
node_modules/
/usr/local/node/lib/
index.js
mymodule/
* assuming mymodule was a core Node.js module

15. require(“mymodule”);
node_modules/
/projects/preso/
index.js
main.js
mymodule/

16. require(“mymodule”);
node_modules/
/projects/
index.js
main.js
mymodule/
preso/

17. require(“mymodule”);
node_modules/
/
index.js
main.js
mymodule/
projects/
preso/

18. require(“mymodule”);
Global load paths also exist,
but don’t use them.

20. Dependency
Resolution Magic!

21. A
B
C
v1.0
v2.0

22. a/
node_modules/
c/
b/
node_modules/
c/
b.js
a.js
c.js
c.js
./node_modules/
v1.0
v2.0

23. a/
b/
b.js
a.js
./node_modules/
c/
c.js

24. Jeff Kunkle
@kunklejr