Validating javascript onChange event
Obviously the code does have some redundancy, which violates the Don't Repeat Yourself principle.
This could be simplified by calling onChange() if allowedInput is falsey or if that is not the case then only when the call to the test method on it returns a truethy value:
const validatedOnChange = (event: ChangeEvent&lt;HTMLInputElement&gt;): void =&gt; {
    if (isDisabled) {
        return;
    }
    if (!allowedInput || allowedInput.test(event.target.value)) {
        onChange({ name, value: event.target.value });
    }
};

One could opt to take the return early approach, which might be more readable and decrease the indentation on the call to onChange() but would have an extra line:
    if (allowedInput &amp;&amp; !allowedInput.test(event.target.value)) {
        return;
    }
    onChange({ name, value: event.target.value });