How to select a dropdown value using JavaScript

Dropdowns provide a way to select a value from a pre-defined list of values such as country name. You can choose a value from a dropdown in two ways. Either you can select a dropdown by index or by the value. Here we have commonly used webpage-based operations on elements using javascript functions such as select a dropdown, set date picker, select radio, set checkbox, etc. this can be used with any Javascript-based automation tool including Protractor.