I can't find error

Question

Where is the error in my code? https://code.sololearn.com/W7SvctXuO73J

Answer 1

1) window.onload accept a function like value not a string..
window.onload= test;
Note that its not a call to test but a reference to test function
2) Make note that for get reference to element (like in getElementById) you have to make sure that browser has yet loaded it and in this case its not true... You have to get 'box' reference then window is loaded