Using JavaScript to auto populate a field based on numeric value of a separate drop down field

Question

Hello, I am trying to set up a simple, I hope, javascript which will enable to me auto populate one field based on the numberic value of another field using Acrobat Pro XI.
Essentially I have 2 drop down fields (we'll call them DD1 and DD2).
DD1 is the sum of 8 preceding drop down values. That sum can be anywhere from 0 - 40. Whatever that sum falls within a range which identifies a rating. The ratings and ranges are below:
0-8: Non-Performer  
9-16: Low Performer  
17-24: Performer  
25-32: High Performer  
33-40: Exceptional Performer
DD2 is where the rating ("non-performer", "low performer", etc.) will be captured. Instead of requiring the user to look at DD1, determine the value, and then identify and input the rating manually, I would like DD2 to auto populate the rating based on the value (sum) in DD1.
For example, if DD1 shows a value of 27 then DD2 would auto populate "High Performer". So how do I write this code or execute this? In excel I would use an if, then statement. Is there something similar in Acrobat Pro XI.
Any help is greatly appreciated. Thank you in advance.

Answer 1

If you use a text field, the custom calculation script could be:
// Custom calculation script for text field
(function () {
    var s = getField("DD1").valueAsString;
    // Blank this field if input is blank
    if (!s) {
        event.value = "";
        return;
    // Convert string to number
    var v = +s;
    // Set this field's value based on the input
    if (v <= 40 && v >= 33) {
        event.value = "Exceptional Performer";
        return;
    if (v < 33 && v >= 25) {
        event.value = "High Performer";
        return;
    if (v < 25 && v >= 17) {
        event.value = "Performer";
        return;
    if (v < 17 && v >= 9) {
        event.value = "Low Performer";
        return;
    if (v < 9 && v >= 0) {
        event.value = "Non-Performer";
        return;
    // If none of the above fit, blank this field
    event.value = "";