[Ie & Firefox compatibility] select operations on JS

Today, I used two drop-down boxes in Ajax to dynamically add options in the SELECT statement. I was not very familiar with the script when I was normal in IE testing but could not be used normally in Firefox, so I checked it online and found that they were a little different when dynamically adding option.

Let's take a look at it and try again later:

Dynamically delete all options in the SELECT statement:
Function deletealloptions (SEL ){
Sel. Options. Length = 0;
}

Dynamically delete an option in the SELECT statement:
Function deleteoption (SEL, indx ){
Sel. Options. Remove (indx );
}

Dynamically Add the option in the SELECT statement:
Function addoption (SEL, text, value ){
Sel. Options. Add (New Option (text, value ));
}

Both IE and Firefox can be tested successfully. I hope you can use it later.