Build the library in learn classes

these is classes course of building library link of course https://www.codecademy.com/paths/web-development/tracks/webdev-intermediate-javascript/modules/learn-javascript-classes/projects/build-a-library

i have got reference Error
super(isCheckedOut);
^

ReferenceError: isCheckedOut is not defined
at new Book (/home/ccuser/workspace/learn-javascript-classes-build-a-library/app.js:45:11)
at Object.

my code link
https://gist.github.com/543230371716f4ffdc457d1487fdc1b7
please Help to solve these issue i am unable to find error
Thanks :smile:

super() is used to call parent method. Why would need to call the constructor multiple times? Also, looking at the parent constructor method, there is only one parameter. So calling the parent constructor should only be done once with the right argument.

thanks i understand now my error thanks for your help :smile: