{singhi}
🏷 tech
Node Resolution Algorithm
← • ☀ 🌙 • 💬 • 📅

require(X) from module at path Y

  1. If X is a core module, a. return the core module b. STOP
  2. If X begins with ‘/’ a. set Y to be the filesystem root
  3. If X begins with ‘./’ or ‘/’ or ‘../’ a. LOAD_AS_FILE(Y + X) b. LOAD_AS_DIRECTORY(Y + X)
  4. LOAD_NODE_MODULES(X, dirname(Y))
  5. THROW “not found”

LOAD_AS_FILE(X)

  1. If X is a file, load X as JavaScript text. STOP
  2. If X.js is a file, load X.js as JavaScript text. STOP
  3. If X.json is a file, parse X.json to a JavaScript Object. STOP
  4. If X.node is a file, load X.node as binary addon. STOP

LOAD_INDEX(X)

  1. If X/index.js is a file, load X/index.js as JavaScript text. STOP
  2. If X/index.json is a file, parse X/index.json to a JavaScript object. STOP
  3. If X/index.node is a file, load X/index.node as binary addon. STOP

LOAD_AS_DIRECTORY(X)

  1. If X/package.json is a file, a. Parse X/package.json, and look for “main” field. b. let M = X + (json main field) c. LOAD_AS_FILE(M) d. LOAD_INDEX(M)
  2. LOAD_INDEX(X)

LOAD_NODE_MODULES(X, START)

  1. let DIRS=NODE_MODULES_PATHS(START)
  2. for each DIR in DIRS: a. LOAD_AS_FILE(DIR/X) b. LOAD_AS_DIRECTORY(DIR/X)

NODE_MODULES_PATHS(START)

  1. let PARTS = path split(START)
  2. let I = count of PARTS - 1
  3. let DIRS = []
  4. while I >= 0, a. if PARTS[I] = “node_modules” CONTINUE b. DIR = path join(PARTS[0 .. I] + “node_modules”) c. DIRS = DIRS + DIR d. let I = I - 1
  5. return DIRS