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;
}
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
