Implement checkbox full selection, inverse selection, and cancellation of JavaScript small script exceptions_javascript skills

Today, when I was implementing a JavaScript script to select all checkboxes, invert selections, and cancel, the page always refreshed instantly after clicking, and all the selected checkboxes were cancelled. After debugging for a long time, I discovered that the tag was missing. The reason for the type attribute is very depressing. I hope I will avoid making this special mistake in the future, so I will record it here.

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After reading the w3c description, I instantly understood that without writing the type attribute, the browser treated it as a submit by default, and the script for my form to be processed was still empty. So the phenomenon of "refresh" occurred!