var str="aab abb aba"
var re1=/\b(a)(\w)\1\b/g
var re2=/\b(?:a)(\w)\1\b/g
console.log( str.match(re1) )  
console.log( str.match(re2) )

function getNextWeekday(dateString) {
    const date = new Date(dateString);
    const day = date.getDay();
    const diff = (day === 0 ? 1 : 8) - day;
    date.setDate(date.getDate() + diff);
    return date.toDateString();
}

console.log(getNextWeekday('2023-10-20'));

var str="dogs cats sheeps car bar star"
var re1=/\b\w+(?:s|ar)\b/g
var re2=/\b\w+(?:s|ar)\b/
var re3=/\b\w+(s|ar)\b/
console.log( str.match(re1) )  
console.log( str.match(re2) )  
console.log( str.match(re3) )  

var regex=/[*+?.|()]/g;
console.log( "(a*b+c?)|(.)".match(regex) );

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

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

console.log(result);

function isPair(s){
  var r=/\(\)|\[\]|\{\}/g;
  while (r.test(s)) s=s.replace(r,"");
  return s=="";
}
console.log( isPair("()") )     
console.log( isPair("((()))") ) 
console.log( isPair("({[]})") )

var str="good wood food cat bat hat";
console.log( str.match(/(g|w|f)ood/g) );

const numbers = [2, 4, 6, 8, 10];

const allEven = numbers.every(function(num) {
    return num % 2 === 0;
});

console.log(allEven);

function aAn(word){
  return (/^(a|e|i|o|u)/i.test(word) ? "An " : "A ") + word;
}
console.log( aAn("apple")) 

var reg2=/^a.c$/    
console.log(reg2.test("abc"))   
console.log(reg2.test("abd")) 
console.log(reg2.test("abbc")) 

const numbers = [10, 23, 45, 60, 78];
const isDivisibleByFive = numbers.some(num => num % 5 === 0);

if (isDivisibleByFive) {
  console.log('Some numbers are divisible by 5');
} else {
  console.log('No numbers are divisible by 5');
}

var word="abcd";
var regstr=word[0]+Array(word.length-1).join(".")+word.slice(-1);  
var reg3=new RegExp("^"+regstr+"$");
console.log(reg3)  

var words=["abc","123","&##"];
for (var r of words){
  var reg=new RegExp(r)
  console.log(reg)
}

var words=["abc","123","&##"];

const students = [
  { name: 'Alice', age: 20 },
  { name: 'Bob', age: 22 },
  { name: 'Charlie', age: 23 }
];

const studentToFind = { name: 'Bob', age: 22 };

const isIncluded = students.includes(studentToFind);

console.log(isIncluded);

var n=1.23456
var a=Math.round(n*100)/100
var b=Math.ceil(n*100)/100
var c=Math.floor(n*100)/100
console.log(a,b,c);

function isPair(s){
  var r=/\(\)|\[\]|\{\}/g;
  while (r.test(s)) s=s.replace(r,"");
  return s=="";
}
console.log( isPair(")()(") )   
console.log( isPair(")(") )    
console.log( isPair("({[})") )

var num=111.1234;
var s=num.toFixed(2)   //s=="111.12"
var a=parseInt(s),
    b=parseFloat(s),
    c= +s
console.log([a,b,c]) 

let arr = [1, 2, 3, 4, 5];
arr.length = 3;
arr.push(6, 7);
console.log(arr.length);

var str="  a b c  ";
console.log(str.trim());

let arr = [1, 2, 3, 4, 5];
arr.length = 3;
console.log(arr.length);
console.log(arr);

var str="Hello World!";
console.log(str.indexOf("world"))
console.log(str.lastIndexOf("world"))
console.log(str.search(/world/i))
console.log(str.search(/word/i))