1let obj = {
2name:"chombi" ,
3age:16 ,
4}
5
6let {name,age,country} = obj;
7console.log(name);
8// chombi
9console.log(age);
10// 16
11console.log(country );
12// undefined 

Here , we are trying extract name , age and country from obj. name and age is present in obj but country is not , so inside country js engine stored undefined and for name , and age we have respective values.

1let arr = [10,20,30,40,50]
2
3let [a,b,c,d,e,f] = arr;
4console.log(a);
5// 10
6console.log(b);
7// 20
8console.log(c);
9// 30
10console.log(d);
11// 40
12console.log(e);
13// 50
14console.log(f);
15// undefined 

Here , we are trying to extract value from array into variables a,b,c,d,e,f. As we are already learnt values will be extracted and stored into variable in the same sequence they are available inside array , so we have value inside a,b,c,d,e but not inside f because at sixth position no value is present and js engine stored undefined in it.

Destructuring object in function parameter

At the time of object destructuring , we have to make sure variable name is same as object key name and write within curly braces.

1function details({name,age}) {
2console.log(name);
3// chombi
4console.log(age);
5// 16
6
7}
8
9let obj = {
10name:"chombi" ,
11age:16 ,
12}
13
14details(obj) // function call

Here , we have passed object as an argument to details function , and we have destructured values in parameter only.

Destructuring array in function parameter

At the time of array destructuring , we have to keep variables between square brackets. Values will be destructured in the same order , they are available in array.

1function details([a,b,c,d,e]) {
2console.log(a);
3// 10
4console.log(b);
5// 20
6console.log(c);
7// 30
8console.log(d);
9// 40
10console.log(e);
11// 50
12
13}
14
15let arr = [10,20,30,40,50];
16details(arr) // function call

Here , we have passed array as an argument to details function , and we have destructured values in parameter only.