Setting multiple values for a multiple select dropdown menu can be done in a few different ways. The first way to set multiple values is to manually select all the values you want. This can be done by pressing the Ctrl key while clicking on each value you want to select. This method is most useful if you only have a few values to select.

The second way to set multiple values is to use the HTML multiple attribute. This attribute allows you to specify that multiple values can be selected. To use this attribute you will need to add the multiple attribute to the select element in the HTML code. For example, if you wanted to set multiple values for a select element called "Colors" you would add the following code:

Red Blue Green

The third way to set multiple values is to use JavaScript. You can use JavaScript to set multiple values by looping through each value and setting the selected attribute to true.

Yes, the setValue() method has always been able to accept integers as arguments. The only change in recent versions of the select element is that it now throws an error if it receives an invalid input. This is to ensure that your data is valid and can be safely used by the select element.

The setValue() method should accept an array as an argument. This works well but you are misusing multiple attribute. I've prepared a snippet in the second thread you opened.