const

const number = 42;

try {
  number = 99;
} catch (err) {
  console.log(err);
  // : TypeError: invalid assignment to const 'number'
  // 
}

console.log(number);
// : 42

const name1 = value1;
const name1 = value1, name2 = value2;
const name1 = value1, name2 = value2, /* , */ nameN = valueN;

const FOO; // SyntaxError: Missing initializer in const declaration

// MY_FAV  7 
const MY_FAV = 7;

console.log(`my favorite number is: ${MY_FAV}`);

// 
MY_FAV = 20; // TypeError: Assignment to constant variable

// 
const MY_FAV = 20; // SyntaxError: Identifier 'MY_FAV' has already been declared
var MY_FAV = 20; // SyntaxError: Identifier 'MY_FAV' has already been declared
let MY_FAV = 20; // SyntaxError: Identifier 'MY_FAV' has already been declared

const MY_FAV = 7;

if (MY_FAV === 7) {
  //  MY_FAV 
  const MY_FAV = 20;
  console.log(MY_FAV); // 20

  // 
  var MY_FAV = 20; // SyntaxError: Identifier 'MY_FAV' has already been declared
}

console.log(MY_FAV); // 7

const MY_OBJECT = { key: "value" };
MY_OBJECT = { OTHER_KEY: "value" };

MY_OBJECT.key = "otherValue";

const MY_ARRAY = [];
MY_ARRAY = ["B"];

MY_ARRAY.push("A"); // ["A"]

const result = /(a+)(b+)(c+)/.exec("aaabcc");
const [, a, b, c] = result;
console.log(a, b, c); // "aaa" "b" "cc"