why-jay

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

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

why-jay

1. Types, Null
2. RAII, GC, Ownership, noexcept
3. Lambdas, Closures, Function Objects
4. Capture Clauses - by Reference, Immutability, Copy
5. (supplement) Solutions for JS callbacks in loops

why-jay

var theThing = null;
var replaceThing = function () {
    var originalThing = theThing;
    var unused = function () {
    if (originalThing)
        console.log("hi");
    };
    theThing = {
        longStr: new Array(1000000).join('*'),
        someMethod: function () {}

why-jay

import makeHttpRequest from 'http-util';

const baseUrl = 'http://foo.com';

export function getUser(id) {
    const response_body = makeHttpRequest(`${baseUrl}/user/${id}`);
    // blah...
}

why-jay

function addX(x) {
    return y => x + y;
}

let add42 = addX(42);
let i = add42(8);
assert(i === 50);

why-jay

// this is a functor
struct add_x {
  add_x(int x) : x(x) {}
  int operator()(int y) { return x + y; }

private:
  int x;
};

// Now you can use it like this:

why-jay

function filterNamesContaining(someStr, names) {
    let rtn = [];
    for (let name of names) {
        if (name.indexOf(someStr) !== -1) { rtn.push(name); }
    }
    return rtn;
}

why-jay

function filterNamesContaining(someStr, names) {
    // filter out names that contain `someStr` as a substring
    return names.filter(name => name.indexOf(someStr) !== -1);
}