bishil06

read directory - opendir vs readdir

create 1000 txt file.
calc 10 times runtime.

bishil06

read directory - async await vs Promise.all

create 1000 txt file to sampleDir directory. calc 1000 times readdir.

async await bottleneck

bishil06

const crypto = require('crypto');

function createMD5(filePath) {
  return new Promise((res, rej) => {
    const hash = crypto.createHash('md5');
    
    const rStream = fs.createReadStream(filePath);
    rStream.on('data', (data) => {
      hash.update(data);
    });

bishil06

Stack I used https://github.com/bishil06/data_structure/blob/main/src/stack/Stack.js

1. convert infix notation to postfix notation
2. operator push stack
3. calculate

bishil06

function *zip(iter1, iter2) {
    const a = iter1[Symbol.iterator]();
    const b = iter2[Symbol.iterator]();
    
    let va = null;
    let vb = null;
    while (!((va = a.next()).done) && !((vb = b.next()).done)) {
        yield [va.value, vb.value];
    }
}

bishil06

function *enumerate(init=0, iter) {
    if (init[Symbol.iterator]) {
        iter = init[Symbol.iterator]();
        init = 0;
    }

    let count = init;
    for(const a of iter) {
        yield [count, a];
        count += 1;

bishil06

function *range(start=0, stop, step=1) {
    while(start < stop) {
        yield start;
        start+=step;
    }
}

console.log(...range(0, 5)); // 0 1 2 3 4
console.log(...range(0, 10, 2)); // 0 2 4 6 8
console.log(...range(1, 20, 3)); // 1 4 7 10 13 16 19

bishil06

class Stack{
    constructor() {
        this.list = [];
        this.top = null;
    }

    push(v) {
        this.list.push(v);
        this.top = v;
    }

bishil06

class Queue {
    constructor() {
        this.list = [];
        this.first = null;
    }

    enqueue(v) {
        if (this.first === null) {
            this.first = v;
        }

bishil06

JS Reverse Array

let arr1 = Array.from({length: 10000000}, (_, i) => i);

Node version 15.8

• reverse method 274ms