In a multiselect dropdown; add/remove item to/from selection through checkbox only or include label

1. How do I select multiple options from a drop down list in a checkbox?
2. How do you multiselect a dynamically populated dropdown based on another dropdown value selection?

How do I select multiple options from a drop down list in a checkbox?

But in this case, multiple options can be selected by holding down the control (ctrl) button of the keyboard. Instead of using the multiple attributes in HTML, you can use jQuery to make the multi-select dropdown more user-friendly and add the checkbox to each option in the multi-select dropdown.

How do you multiselect a dynamically populated dropdown based on another dropdown value selection?

It's simple: just add an onClick to call a function every time the options are checked (or unchecked), and then, loop the checkboxes looking for the cheked options, concatenating their texts and showing it at the main label of the select.