[solved]Please teach me why property "width" is null?

Question

I'm beginner of programming (and English).
I don't know why I could get canvas' width.
https://code.sololearn.com/Wct92EwbeVWJ/?ref=app

Answer 1

probably it is treating ”test” as a whole string including those ”” characters as well .
So you need to select id this way ,

document.getElementById("”test”"

Or you could just use right characters (i.e. "test") if you want only test to be interpreted as string.

Answer 2

The value for id attribute of the <canvas> is wrapped with slanted quotation marks. This in turn, makes the browser ignores the attribute and its value.

Answer 3

// your incorrect code id=”test”
// correct code id="test"

different symbol ” & "

https://code.sololearn.com/WEOdYenUT4HB/?ref=app

Answer 4

Thank you for every answers.

I could get property width by erase quotation marks of id="test".