onPaste + setFieldValue does not work as intended

[gnesher]

Bug report

Current Behavior

When trying to setFieldValue within onPaste callback prepends the field value instead of replacing it.

Expected behavior

setFieldValue should replace the field value

Reproducible example

The templates are outdated (very old React/Formik versions) I couldn't get them to work without refactoring the entire thing.
This is the code I'm using

onPaste={async (event: ClipboardEvent<HTMLInputElement>) => {
  const reg = /:(?<port>[0-9]+)/
  const valueArray = event.clipboardData.getData('text/plain').split(reg);
  if (Number(valueArray[1])) {
    setFieldValue('url', valueArray[0]);
    setFieldValue('port', valueArray[1]);
  }
}

Your environment

Software	Version(s)
Formik	2.2.9
React	17.0.2
TypeScript	4.4.2
Browser	Chrome latest
npm/Yarn	Yarn
Operating System	Ubuntu 20

[gnesher]

event.preventDefault() seems to sort it, not sure if this is just my miss here

[ChronicusUA]

Seems like it is not formik error itself. Yes event.preventDefault() should fix your problem.
There is an example without formik and it works as you described:

import { useState } from 'react';

export const RegularForm = () => {
    const [firstName, setFirstName] = useState<string>("");
    const [lastName, setLastName] = useState<string>("");

    return (
        <form>
            <input
                type="text"
                name="firstName"
                value={firstName}
                onChange={(e) => setFirstName(e.target.value)}
                onPaste={(event) => {
                    const valueArray = event.clipboardData.getData('text/plain').split(" ");

                    setFirstName(valueArray[0]);
                    setLastName(valueArray[1]);
                }}
            />
            <input
                type="text"
                name="lastName"
                value={lastName}
                onChange={(e) => setLastName(e.target.value)}
            />
        </form>
    );
};