Regex/move and improve (#2006)

* Create folder and readme.md

- Created sub-folder "Check for special characters" in the Regular Expressions folder.
- Added readme

* Update and rename specialcharacter.js to specialcharacter.js

- Moved the script to the new created folder in Regular Expressions.
- Refactored/fixed the code:
-- Renamed regex variable to disallowedChars for clarity.
-- Escaped special characters inside the regex to correctly match (, ), [, and ].
-- Added detailed comments explaining the purpose and structure of the regular expression.
-- Replaced placeholder field name with a variable for easier reuse and readability.
-- Improved error messaging to clearly inform users about invalid input.

* Delete Client-Side Components/Client Scripts/Field Validation directory

Deleted the old folder. Files in the folder have moved to the Regex folder.

* Update readme.md

Expanded and clarified the Readme. Also included in the description the updated script.

Author: WillemZeiler

Client-Side Components/Client Scripts/Field Validation/README.md

@@ -0,0 +1,26 @@
+# Special Characters Validation (onChange Client Script)
+
+This script validates user input in a specific field and prevents the use of disallowed special characters.  
+It is designed to run as an **onChange client script** .
+
+## Functionality
+
+- When the user changes the value of a field, the script checks if the new value contains any special characters.
+- If disallowed characters are found, the field is cleared and an error message is displayed to the user.
+- The validation uses a regular expression that includes common special characters such as `~`, `@`, `|`, `$`, `^`, `<`, `>`, `*`, `+`, `=`, `;`, `?`, `` ` ``, `'`, `(`, `)`, `[`, and `]`.
+
+## How to Use
+
+1. Add the script as an **onChange client script** on the field you want to validate.
+2. Replace the placeholder `'<your_field_name>'` in the script with the actual field name.
+3. Customize the regular expression if you want to allow or block different characters.
+
+## Example Behavior
+
+- Input: `Hello@World` → ❌ Invalid → Field is cleared, error message shown.
+- Input: `HelloWorld` → ✅ Valid → No action taken.
+
+## Notes
+
+- The script uses `g_form.clearValue()` to reset the field and `g_form.showErrorBox()` to display feedback.
+

Client-Side Components/Client Scripts/Field Validation/specialcharacter.js

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+function onChange(control, oldValue, newValue, isLoading, isTemplate) {
+    // Exit early if the form is loading, in template mode, or the new value is empty
+    if (isLoading || newValue === '') {
+        return;
+    }
+
+    /**
+     * Define a regular expression to match disallowed special characters.
+     * Breakdown of the pattern:
+     * [~@|$^<>*+=;?`'\)\(\[\]]
+     * * - Square brackets [] define a character class, meaning "match any one of these characters".
+     * - ~ @ | $ ^ < > * + = ; ? ` ' ) ( [ ] : These are the characters being checked.
+     * - Characters that have special meaning inside a character class (like `(`, `)`, `[`, `]`) must be escaped with a backslash `\`.
+     */
+    var disallowedChars = /[~@|$^<>*+=;?`'\)\(\[\]]/;
+
+    var fieldName = '<your_field_name>'; // Replace with the actual field name being validated
+
+    // Check if the new value contains any disallowed characters
+    if (disallowedChars.test(newValue)) {
+        g_form.clearValue(fieldName);
+        g_form.showErrorBox(fieldName, 'Special characters are not allowed.');
+    }
+}