Formik: set value based on previous value

[wilhei]

Is there a possibility to set a formik value based on the previous value?

Here a simple example:

  const onButtonClick = () =>{
    Array.from(Array(5).keys())
     .forEach((num) => formik.setFieldValue("testvalue", formik.values.testvalue + num));
    };
  }

The problem is, that if some functions run async parallel, we end up with a result, where only one num was added, instead of a sum of all.

In react's useState "Dispatch" we have the possibility to use a function as value, which has the previous item as parameter:

const [testValue, setTestvalue] = React.useState(false);
setTestvalue((prev) => prev + num)

So I would expect something like this with formik:

const onButtonClick = () =>{
    Array.from(Array(5).keys())
     .forEach((num) => formik.setFieldValue("testvalue", (prev) => prev + num));
    };
  }