why-jay

// domElems is an array of DOM elements of length 5
for (var i = 0; i < domElems.length; ++i) {
    ((j) => {
        domElems[j].addEventListener('click', () => {
            console.log(j);
        });
    })(i);
}

why-jay

domElems.forEach((elem, i) => {
    elem.addEventListener('click', () = {
        console.log(i);
    });
});

why-jay

for (let i = 0; i < domElems.length; ++i) {
    domElems[i].addEventListener('click', () => {
        console.log(i);
    });
}

why-jay

const Bluebird = require('bluebird');
const fs = Bluebird.promisifyAll(require('fs'));

const getFilenamesContainingMichaelAsync = Bluebird.coroutine(function* (path) {
    const filenames = yield fs.readdirAsync(path);
    return filenames.filter(name => name.indexOf('Michael') !== -1);
});

Bluebird.coroutine(function* () {
    const filenamesContainingMichael = yield getFilenamesContainingMichaelAsync('~/some_dir');

why-jay

// immutable version
const map = arr =>
    arr.reduce((prev, cur) => prev.concat(cur), []);
    
// mutable version
const map = arr =>
    arr.reduce((prev, cur) => {
        prev.push(cur);
        return prev;
    }, []);

why-jay

List<Action> actions = new List<Action>();
for (int counter = 0; counter < 10; counter++)
{
    int copy = counter; // block-scoping in action!!
    actions.Add(() => Console.WriteLine(copy));
}

why-jay

List<Runnable> actions = new ArrayList<Runnable>();        
for (int counter = 0; counter < 10; counter++)
{
    final int copy = counter; // notice the `final` keyword!
    actions.add(() -> { System.out.println(copy); });
}

why-jay

List<Runnable> actions = new ArrayList<Runnable>();        
for (int counter = 0; counter < 10; counter++) {
    final int copy = counter; // notice the `final` keyword!
    actions.add(new Runnable() {
        public void run() { System.out.println(copy); }
    });
}

why-jay

#include <iostream>
#include <thread>
#include <vector>

using namespace std;

int main()
{
	vector<thread> workers;
	for (int i = 0; i < 5; ++i)

why-jay

#include <chrono>
#include <iostream>
#include <thread>
#include <vector>

using namespace std;

int main() {
	vector<thread> workers;