Why error if i click on anywhere

Question

It said cannot read property of classList of null https://code.sololearn.com/Wst08cUjJzZN/?ref=app

Answer 1

place your js code inside this function
window.onload=function(){

}
Use search bar to search for similar question if you want to know what window.onload do and why is it used ,by default sololearn places js script inside head element and so it gets executed before the body part

Answer 2

乂۝丹ⓨㄩک廾۝乂〖թг๏〗
Kirti
John Wells
Aad Hoogenboom
AZHAGESAN S
Namit Jain [INACTIVE]