const in javascript

1const age; // errror as const cannot be kept un-initialized;
2const age = 20 ; 
3const age = 21 , // error as once declared const variable cann't be
4// re-declared in same scope or different scope. 
5

1const b = 1; // this variable unique and can't change it. 
2

1// var declares a variable, meaning its value will vary. 
2// const declares a constant, meaning its value will remain 
3// consistant and not change. 
4// If your variable changes throughout the program or website, 
5// declare it using a var statement. 
6// Otherwise, if its value does not change, declare it using 
7// a const statement. 
8
9const myConst='A const does not change.';
10
11var myVar='A var does change.';
12
13var myVar=2;

1const value = 10;
2const constant = value;

1const elem = document.getElementById('elementID');

1/*The destructuring assignment syntax is a JavaScript expression that
2makes it possible to unpack values from arrays, or properties from objects,
3  into distinct variables.*/
4  let array = [2,3]; 
5  [a,b] = array;// unpacking array into var a and b
6  console.log(a); //output 2
7  console.log(b); //output 3
8  let object = {name:"someone",weight:"500pounds"};
9  let {name,weight} = object; // unpacking object into  var name and weight
10  console.log(name);// output someone
11  console.log(weight);//output 500pounds
12
13//it i similar as doing this
14/*
15var a = array[0];
16var b = array[1]
17var name = object.name;
18var weight = object.weight;
19
20 */