This is an example of how to change the quantity selector on the product detail page from a "+-" button type to a dropdown in the Shopify theme "Dawn." The original selector has various events associated with it, so these are maintained while the new dropdown controls are used to operate them indirectly.
Example of setting the quantity selector to a drop-down type in the Shopify theme "Dawn"

[How to set it up] Add a custom Liquid section to the product information block in the product template and insert the code.

