hash function gist

index.js

const crypto = require("crypto");

function hash(data, callback) {
  let counter = 0;
  let result = [];
  
  let func = () => {
    if(counter === data.length) {
      callback(result);
      return;
    }
    
    let md5 = crypto.createHash("md5");
    md5.update(data[counter]);
    
    result.push(md5.digest('hex'));
    
    counter++;
    // process.nextTick adds to the micro task queue which is always executed before the task queue (timer functions push to task queue).
    // changing this to setTimeout will satisfy unblocking the event loop
    setTimeout(func);
  };
  
  func();
}

hash(["test", "another test", ""], console.log);
setTimeout(() => {
  setTimeout(() => console.log("This should be printed before the hashes"));
});
/* should print
['098f6bcd4621d373cade4e832627b4f6', 
 '5e8862cd73694287ff341e75c95e3c6a',
 'd41d8cd98f00b204e9800998ecf8427e'] */

module.exports.hash = hash;