dedup words (streaming process from stdin)

dedup.js

var readline = require('readline');
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

let hash = {};

rl.on('line', function(line){
    if(hash[line]) {
        // skip
    } else {
        hash[line] = 1;
        console.log(line);
    }
})