+ 1

Whats the logic behind this code snippet?? Wen I run it, it returns [3,6,9,3]

JavaScript Quiz 🏆 if you run this code what do you expect to see the output? const num = [ 3, 6, 9 ]; num.push(num.push(num.pop( ))); console.log(num);

12th Jan 2021, 3:02 PM
Rex Nerdy
Rex Nerdy - avatar
4 Respostas
+ 3
When you see nested function/method calls like this, start working your way out from the inner most call, head out to the outer most call. Knowing that ... - pop() removes last item off an array, and returns the removed item. - push() adds new item at the end of an array, and returns the updated array size. So let's begin, initially <num> was [ 3, 6, 9 ]. Inner most call - num.pop() Removes last item (9) and return the removed item (9) to the middle call. <num> then becomes [ 3, 6 ]. 9 was passed off to the middle call - num.push() Adds 9 back into <num> at the end, and return updated array size (3) to the outer call. <num> by then becomes [ 3, 6, 9 ] again. 3 was passed off to the outer call - num.push() Adds 3 into <num> at the end, thus <num> becomes [ 3, 6 ,9, 3 ]. Then log array <num> in JS console.
12th Jan 2021, 3:36 PM
Ipang
+ 2
pop removes the last element of a list and returns the popped out element push adds a element at the end of the list and returns the new length of the list num.push(num.push(num.pop())); // num = [3, 6] num.push(num.push(9)); // num = [3, 6, 9] num.push(3) // num = [3, 6, 9, 3]
12th Jan 2021, 3:39 PM
Stefanoo
Stefanoo - avatar
+ 1
Where did the last 3 comws fr0m??
15th Jan 2021, 7:43 AM
Rex Nerdy
Rex Nerdy - avatar
+ 1
Rex Nerdy Copy & paste this in Js tab of a new web code, may it help to understand const num = [ 3, 6, 9 ]; console.log( `Originally, num = [${num}]\n` ); let result1 = num.pop(); // inner most call console.log( `num.pop() removes ${result1} and returns ${result1}` ); console.log( `num = [${num}]\n` ); let result2 = num.push( result1 ); // middle call console.log( `num.push() appends ${result1} and returns ${result2}` ); console.log( `num = [${num}]\n` ); let result3 = num.push( result2 ); // outer call console.log( `num.push() appends ${result2} and returns ${result3}` ); console.log( `num = [${num}]\n` );
15th Jan 2021, 8:30 AM
Ipang