[solved]Why can code_01 get property width,and code_02 can't ?

Question

These script and jsfile are same code.
When is jsfile of the 3files(html,css,js) read?
https://code.sololearn.com/Wct92EwbeVWJ/?ref=app
https://code.sololearn.com/Wp856UEfIxk6/?ref=app

Answer 1

Sololearn places javascript file inside head tag , so in code1 the script is executed before html dom is loaded and so there is no element with id "test1" yet.

Answer 2

Thank you for Easy-to-understand explanation.And fast answer!