# Summing up two text fields dynamically

> Trigger type: **JavaScript** Action type: **Value**

Trigger type: **JavaScript** Action type: **Value**

This advanced logic sums up two text fields, based on the condition that the user interacts with the corresponding text fields.

At runtime, if the business user interacts with text fields `A` and `B`, the `Total` field gets automatically filled in, displaying the sum of A and B.

1. Open or create a **Form** file in Studio.
2. Add three **Text Field** components into your form.
3. Name two of the text field components as `A` and `B`, and name the third one as `Total`. Pay attention to their **Property Names**, as you use those in your advanced logic.

   Optionally, you can set the `Total` text field component as **Disabled**, so business users cannot interact with it.
4. Go to the **Logic** tab of the `Total` field component.
5. Add a logic and name it `"dynamic sum"`.
6. Select the **Javascript** trigger type, and enter the following script in the **Text Area** section:
   ```
   result = true;
   return result;
   ```

   The above snippet detects if there are any changes in the text fields, i.e., the user interacts with the text fields, and triggers the action to sum up the fields.
7. Add an action and name it `"a+b"`.
8. Select the **Value** action type, and enter the following script in the **Value (Javascript)** section:
   ```
   result = (+data.a) + (+data.b);
   return result;
   ```

   Replace `a` and `b` with the field keys values of the text field components.
9. Save the action and the logic.
10. Save the component.