Inserts predefined text into a text box when the user presses enter or clicks okay
```javascript
// ==UserScript==
// @name Insert Predefined Text
// @namespace http://tampermonkey.net/
// @version 0.1
// @description Inserts predefined text into a text box when the user presses enter or clicks okay
// @match *://*/*
// @grant none
// ==/UserScript==
(function() {
'use strict';
// Set the predefined text here
var predefinedText = "This is the predefined text.";
// Add an event listener for keydown events
document.addEventListener('keydown', function(event) {
// Check if the key pressed was enter
if (event.key === 'Enter') {
// Get the active element (the one currently selected by the cursor)
var activeElement = document.activeElement;
// Check if the active element is a text box
if (activeElement.tagName === 'TEXTAREA' || (activeElement.tagName === 'INPUT' && activeElement.type === 'text')) {
// Insert the predefined text into the text box with a space before it
activeElement.value += ' ' + predefinedText;
}
}
});
})();
```