var arr=[1,2,3,4,5];
console.log(arr.reduce((a,b)=>a+(b%2?1:0),0)); 
console.log(arr.reduce((a,b)=>a+(b%2?0:1),0));

var arr1=[1,2,3,4,5];
var arr2=[6,7,8,9,10];
var result=arr1.map(x=>x*x).reduce((a,b,i,ar)=>a.concat(ar[i],arr2[i]),[])
console.log(result);

function combine(...arrays) {
  return arrays.reduce((acc, arr) => [...acc, ...arr], []);
}

const result = combine([1, 2], [3, 4], [5, 6]);
console.log(result);

var chars=[];
for (var i=97;i<123;i++){
  chars.push(String.fromCharCode(i));
}
console.log(chars.join(""))

const obj = {
  valueOf() {
    return 42;
  }
};

const result = obj + 8;
console.log(result);

function trickyFunction() {
    var a = 10;
    var b = a;
    b = 15;

    const obj1 = { x: 1 };
    const obj2 = obj1;
    obj2.x = 5;

    console.log(a + ' ' + b + ' ' + obj1.x);
}

trickyFunction();

function trickyFunction() {
  var x = 10;
  if (x > 5) {
    let y = x * 2;
    x = y;
  }
  return x;
}

console.log(trickyFunction());

function trickyFunction() {
  var obj = { a: 1 };
  var anotherObj = obj;
  obj.a = 2;
  obj = { a: 3 };
  anotherObj.a = 4;
  return obj.a + anotherObj.a;
}

console.log(trickyFunction());

async function fetchData() {
  let data = 'initial';

  const promise = new Promise((resolve) => {
    setTimeout(() => {
      resolve('fetched');
    }, 1000);
  });

  promise.then((result) => {
    data = result;
  });

  return data;
}

fetchData().then(console.log);

const WM = new WeakMap();
let obj = {};
let anotherObj = {};
WM.set(obj, 'object data');
WM.set(anotherObj, 'another object data');
obj = null;

console.log(WM.has(obj));
console.log(WM.has(anotherObj));

const mySet = new Set();
mySet.add(10);
mySet.add(20);
mySet.add(10);
mySet.add(30);

console.log(mySet.size);

function* customGenerator() {
    yield 'Hello';
    yield 'World';
    return 'Done';
}

const gen = customGenerator();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);

const myObject = {
  a: 1,
  b: 2,
  c: 3,
  [Symbol.iterator]: function* () {
    for (let key of Object.keys(this)) {
      yield this[key];
    }
  }
};

const iter = myObject[Symbol.iterator]();
console.log(iter.next().value);
console.log(iter.next().value);
console.log(iter.next().value);

var obj = { a: 10, b: 20 };

with (obj) {
  var result = a + b;
}

console.log(result);

function trickyFunction() {
  let a = 5;
  let b = '5';
  let c = 5;

  if (a == b && b === c) {
    console.log('Condition 1');
  } else if (a === c || b == c) {
    console.log('Condition 2');
  } else {
    console.log('Condition 3');
  }
}

trickyFunction();

var str="My name is John";
var words=str.split("");
console.log(words);

function displayArguments() {
  console.log(arguments.length);
  console.log(arguments[0]);
  console.log(arguments[2]);
}

displayArguments('Hello', 'World', 'JavaScript', 'Quiz');

function decode(str){
  var chars=str.split("");
  for (var i=0;i<chars.length;i++) 
    chars[i]=String.fromCharCode(chars[i].charCodeAt()-1);
  return chars.join("");
}
function encode(str){
  var chars=str.split("");
  for (var i=0;i<chars.length;i++) 
    chars[i]=String.fromCharCode(chars[i].charCodeAt()+1);
  return chars.join("");
}
var s="abcde"
s=encode(s);
console.log("encode:",s)
s=decode(s);
console.log("decode:",s)

var str="Hello beautiful World!";
console.log(str.slice(16,21))
console.log(str.substring(16,21))
console.log(str.slice(16,-1))

let str = "Hello, World!";
let result = str.substring(7, 12);
console.log(result);

var str="abcdef";
console.log( str.match(/./g) )   
console.log( str.match(/../g) ) 
console.log( str.match(/.../g) )