Writing JS in HTML element throws an error

manu.120 · 2024-09-24T00:45:23.670Z

Hi,
I have an html element on page inside which I am running a js. The js has a variable which takes value from db. The code inside HTML is given below

When I run this page i get the following error.
“run_debug.js:592 Bug in custom html:
SyntaxError: Identifier ‘winSliderMsg’ has already been declared”

The error doesn’t appear on first page load but occurs only when i refresh the page. I haven’t declared this variable again. Also, if I assign a simple string to the variable like
let winSliderMsg =“test msg”;
the error disappears.

Any idea of why this is happening?

rico.trevisan · 2024-09-24T01:14:12.802Z

I think you forgot to paste the code.

dorilama · 2024-09-24T06:31:11.903Z

manu.120:

The error doesn’t appear on first page load but occurs only when i refresh the page. I haven’t declared this variable again.

the code is executed multiple times by bubble (e.g. when the dynamic data you use changes) so your code needs to be ready for that. this is a pattern that can be useful.

on a side note including user-generated dynamic data in a string that is then evaluated as javascript (it’s what is done with scripts in html elements) is a security risk.

system · 2024-12-03T00:45:53.043Z

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