Roll20 Wiki

Main Article: Sheet Worker Scripts

Auto-calculating Attributes

Example 1

Your best bet would be to avoid the autocalc fields entirely if you can. Monitor the two other fields and when they change, have a sheetworker that adds them up to the new value. Then you can refer to the new value in other calculations much easier.

on("sheet:opened change:stat_a change:stat_b", function() {
    getAttrs(["stat_a", "stat_b"], function(values) {
        setAttrs({
            "foo_modchars": parseInt(values["stat_a"]) || 0 + parseInt(values["stat_b"]) || 0
        });
    });
});

Example 2

(credit: GiGs)

I remember seeing a script someone wrote to allow you to use autocalc fields within sheet workers, but it's just simpler to use Rabulias's approach(see example 1 above).

Add the relevant stats to the on(change:) line, and duplicate the calculation within the sheet worker.

I generally don't put my working in the setattrs call, but before it so i can more easily check it. Something like

on("sheet:opened change:stat_a change:stat_b", function() {
  getAttrs(["stat_a", "stat_b"], function(values) {
      var stat_a = parseInt(values["stat_a"],10)||0;
      var stat_b = parseInt(values["stat_b"],10)||0;
      var output = stat_a + stat_b;
      setAttrs({
        "foo_modchars": output
      });
  });
});

Helper Functions

This section is for useful functions that aren't complete sheet workers, but are useful to use in sheet workers.

Function: parseValues

(credit: GiGs) Many sheet workers have a bunch of lines like this:

      var stat_a = parseInt(values["stat_a"])||0;
      var stat_b = parseInt(values["stat_b"])||0;

You might also have lines like this:

setAttrs({
   "foo_modchars": parseInt(values["stat_a"],10) || 0 + parseInt(values["stat_b"],10) || 0
});

It gets tedious typing out all that. With the function below, you would instead write them as:

var stat_a = parseValues(values,"stat_a");
var stat_b = parseValues(values,"stat_b");
setAttrs({
   "foo_modchars": parseValues(values,"stat_a") + parseValues(values,"stat_b")
});

I think that's a lot easier to read. Here's the function:

parseValues

Place this at the start of your script block, and you'll be able to use it in all your sheet workers.

const parseValues = (values, stat, type='int') => {
     if(type === 'int') return parseInt(values[stat])||0;
     else if(type === 'float') return parseFloat(values[stat])||0;
     else if(type === 'str') return values[stat];
};

By default, it returns an integer. If you call it with a second parameter, it will return either a float or a string:

parseValues(values, stat) or parseValues(values, stat, 'int') - returns an integer.
parseValues(values, stat,'float') - returns a Float (a number that is not an integer)
parseValues(values, stat, 'str') - returns the value as text. (Not really needed!)

This function does handle variable attribute names. If you were in a loop and creating attributes like, "stat" + i it will work fine.