javascript code to get select drop-down list value_form effects

For example, when using DWR, if you want to pass the parameters of the drop-down box to the background, you need to obtain the value of the drop-down box first.
In fact, it is very simple to get the value of the drop-down box.
The most critical piece of code is:

Copy code The code is as follows:

onchange= "show(this.options[this.options.selectedIndex].value);"

onchange="show(this.options[this.options.selectedIndex].value);"
show is a custom function name.

this.options[this.options.selectedIndex].value is the protagonist!