Code 800A0404 issue

So I am new to HTML and Javscript, and I 'm trying to setup p5.js , however I received windows script host problem Code 800A0405 source microsoft JScript compilation error…how can I fix this ? Please help me!!! Thanks!!!

Mary, can you provide details of what you were trying to do there? Are you working on an online p5.js editor? If you share your link/resources and tell us what you did, we would be in a better position to help.

To get started with p5.js you can look into other options like this one. In a nutshell, you use any text editor. You setup a folder in your personal document section in your computer. In this folder, you need to have two files (based on the link I just shared), one file named index.html an another file named sketch.js and that’s it. For the html, add the code:

    <script src=""></script>
    <script src="sketch.js"></script>

for the javascript file, you start with this, which you can change as you progress in you learning:

function setup() {


function draw() {
  ellipse(50, 50, 80, 80);

So for instance, you can modify the above code so to change the background every second:

function setup() {

function draw() {
  ellipse(50, 50, 80, 80);

function setBackgorund(){
    let r=random(220);      //Red
    let g=0;                //Green
    let b=random(100,180);  //Blue

After you saved both files, you click on the idex.html and it should launch in a browser and you should see a canvas where its background changes color every second.

You can check another modified version of the code above here next:

See the Pen p5js-BasicDemo by kfrajer (@kfrajer) on CodePen.


1 Like

Easiest & fastest recipe to run “.js” sketches under p5.js: :running_man:

  • Install any Firefox-based browser in your OS and use it to open your “index.html” file: :fox_face:
  • Install Notepad2 or Notepad++ (or both) in your OS and use it to type in your “sketch.js” file there: :scroll:
  • You can setup those text editors to use UTF-8 and LF line endings for better compatibility. :bulb:
  • Here’s my minimum “index.html” template file which can run most “sketch.js” files out there: :play_or_pause_button:
<!DOCTYPE html>

<meta charset=utf-8>
<meta name=viewport content=width=device-width,initial-scale=1>

<script defer src=></script>
<script defer src=></script>

<script defer src=sketch.js></script>
  • Now you can create a folder and place both “index.html” & “sketch.js” files inside it. :file_folder:
  • W/ Firefox opened, drag & drop the “index.html” file into it. :computer_mouse:
  • It should automatically run your “sketch.js” code there.
  • Otherwise, if there’s anything wrong in your code, hit the F12 key or the key combo CTRL + SHIFT + J in order to open the browser’s console, and check for any error messages there.

Here’s some p5.js sketch running online w/ both “index.html” über minimum file & the “sketch.js” code file: :smile_cat:


i’m having the same problem i downloaded p5 zip and trying to open any file inside result in the same
"error message "
what should i do

please help us with more details,
esp. as you post in a one year old topic.

  • what exactly you download
  • how unzip
  • and start what / how

++ also tell us more about your environment / OS …

example, for a other topic i play
i select / File / Download /
and save local

  • on a WIN 10 PC unzip
  • and double click on index.html
    and select my firefox browser to run it.

i went to the offecial p5* site i downloaded both the complete and the single uncompressed files
both resulting on error in every try to open any file

It works fine here:

  1. Download:
  2. Extract files in downloaded ZIP to a folder.
    You MUST do this and work with the extracted folder!
  3. I used this example:
    I copied it to the sketch.js example in the “empty-example” folder.
  4. The sketch worked; I opened index.html in Firefox, Chrome, Edge and Internet Explorer successfully.
  5. You MUST open the index.html file.


You WILL get an error if you click on any JavaScript file (one example):

1 Like

your video shows / explains nothing about

  • what action ( start program?? ) you made and
  • what ERROR you got.

also you not explained what you want to do?

if you want learn processing in browser with P5.js
please start with the online editor

later, when you have some working code,
what for ever reason you want run “OFF_LINE”
you can download the project zip to your PC.
and run it with double click on index.html.

and also note that you have a good working environment
if you download processing 3.5.3 here and install p5.js MODE

in both cases you not need to do what you just try to do

and as @glv already told you, you not ( try to ) start ( double click )


but here a snap of doing that under Win 10:

-1- download

-2- extract

-3- get

-4- reproduce you mistake ( and get error )

-5- go down to the provided empty example
and double click


and see a empty browser window ( here firefox ) open.

hope that gives you the right idea how to use/start p5.js

sorry her’s the vedio

you want to say that p5 writes on text file?

ok Sirine Benyounes,
we told you 2 times already that
you NOT have to try to execute p5.js … like a app
as it is called from HTML ? like a library? sorry that poor wording.

hm, could do, but that is not the point here.

you do what i show in the pictures, call

  • by browser
  • by double click

and you make a sketch.js file by any editor with your code.

again if you not get the basics running you please work in the online editor
to learn the coding … of p5.js “language”

your way is not good for a beginner start
as it misses the working environment what is provided
by the online editor or by the processing 3.5.3 p5.js mode…

i’m sorry i still don’t get this dealing with a libary means the code would work on any text file?
"my way is not good as a biginner " what do you mean ?
i watched the coding train and i thought i could find a similar program at the site he provided
u said there’s a p5 mode on processing any info about how to enable that ?
i hope i didn’t any how disturb you i’m just trying to undrestand …

well, i see that
might be much too complicated for a very start.

also forget the processing IDE p5.js mode, as it might be also too difficult to install.

work only here:

you can make an account ( sign up )
to save your code ( online )

and in a month, if you still think you need to work offline / local
show me the link to your running project, and we try from there again.

Clearly the official tutorials are too confusing for @tcach55 . :dizzy_face:

You can forget all about those and try out my “easiest” recipe posted in this very forum thread: :angel:

Here’s the example sketch’s source code: :nerd_face: