javascript code to dynamically set the value of a known select option_form effects

Copy code The code is as follows:

funtion setSelectOption(a, b){//a =>select id name, b=>Known option value

for (i=0;i<$(a).length;i) //$(a) Simple way to get the id of a, The premise is that prototype.js must be referenced
if($(a).options[i].value == b){//Traverse select
$(a).options[i].selected=true; //Select specific value
break;
}