Core modules

These are the modules comes preinstalled with node.js like the path module we used earlier.

const path = require("path"); 

const dirUpload = path.join(__dirname, "uploads"); 

console.log(dirUpload); 

The util module:

const path = require("path"); 
const util = require("util"); 

util.log(path.basename(__filename)); 

util.log("  ^ the name of the current file."); 

28 Apr 22:37:34 - core.js
28 Apr 22:37:34 -   ^ the name of the current file.

We have dozens of such modules.

const v8 = require("v8"); 

console.log(v8.getHeapStatistics()); 

{
  total_heap_size: 4505600,
  total_heap_size_executable: 524288,
  total_physical_size: 3408264,
  total_available_size: 2194589720,
  used_heap_size: 2376352,
  heap_size_limit: 2197815296,
  malloced_memory: 8192,
  peak_malloced_memory: 123200,
  does_zap_garbage: 0,
  number_of_native_contexts: 1,
  number_of_detached_contexts: 0
}

readline module:

const readline = require("readline"); 

const rl = readline.createInterface({
    input: process.stdin, 
    output: process.stdout
}); 

rl.question("What is you name? ", answer => {
    console.log(`Hello ${answer}`); 
    process.exit(); 
});