Adjusting a javascript variable dynamically using Greasemonkey during execution

I am facing an issue with a webpage that contains a .js script. The page includes the following code:

    <script>
        Client.includeJS(
            'js/scratchticket.js'
        );
    </script>

The scratchticket.js file contains the following code:

$(document).ready(function() {
        ...
        var xxx = 100;    
        ...
  });

I have tried various methods in Greasemonkey to change the value of the variable "xxx" to 200 but have been unsuccessful. I even attempted to block the scratchticket.js file with adblock and copy the entire code into a Greasemonkey script to edit the variable, but the changes are not taking effect. The page keeps showing 'loading...' when it should execute the code.

Does anyone have any ideas on how to successfully alter the variable in another way?

javascriptvariablesfirefoxgreasemonkey

Answer №1

The problem lies in the incorrect information provided by @Quasimodo's clone answer, as it actually executes at the opposite time.

As stated in the wiki reference:

document-end is the standard behavior for Greasemonkey (see DOMContentLoaded). This is the default if no value is provided.

If you are experiencing issues with your userscript executing too late, simply add this directive at the beginning of your script:

// @run-at document-start

Give that a try and see if it resolves your problem!

Answer №2

In order to receive the most relevant answers, it is crucial that you provide additional information and code. It is essential to understand the timing of when the userscript executes and whether any permissions are required.

If your goal is simply to update a JavaScript code with an initial value, you might want to consider monitoring the beforescriptexecute event. Once triggered, you must first confirm if the event target corresponds to the script you intend to modify. After identification, you can then locate and replace the necessary JavaScript line. To execute this process effectively, you will need to halt the original script's execution and embed the revised code within a new <script> tag in the Document Object Model (DOM), as direct manipulation of loaded scripts is not feasible.

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