# Dynamic Js Execution

### 1. Inherit From BaseTBContract

Import `BaseTBContract.sol` contract and extend from it.

### 2. Constructor

When deploying the contract, ensure you set the correct values for **watchTowerAddress,** **sourceCode** within your contract:

* **watchTowerAddress**: `0xEcd0EeD24Ed6a54d05a07125c4ccb809b3A09868`.
* Ethereum Mainnet Address: `0x48C101d60F6f8a9589fa74e10da62460219B53e6`.
* **sourceCode**: "`Place your JS code here inside quotes`".

### 3. Submitting a Request

In your contract, to execute JS code on Truebit, call the `_requestExecution` function. This will trigger the task execution on the Truebit platform.

To call the  **`_requestExecution`** , you must:

1. Define the method signature string.
2. Encode all parameters using **`abi.encode`**.
3. Specify the execution type as: `DOTypes.ExecutionType.EMBEDDED_FUNCTION`.

#### Method Signature

**The method signature must follow a strict format.** It begins with the method name (in this case, `"function"`), followed by parentheses containing the parameter definitions, separated by commas.

Example:

```solidity
function(uint256)
```

#### Filling The Payload

Once the method signature is defined, you must fill the payload with the values for the parameter defined on the signature, and encode it by using `abi.encode(...)`.

#### Call \_requestExecution

Finally, you call \_requestExecution() with:

* The method signature (string).
* The encoded payload (bytes).
* The execution type: `DOTypes.ExecutionType.EMBEDDED_FUNCTION` .

```solidity
// Prepare the payload for the function execution
bytes memory payload = abi.encode(
    input     // The input parameter for fibonacci calculation
);
// Submit the execution request to the Truebit network
uint256 wtExecutionId = _requestExecution(
    "function(uint256)",
    payload,
    DOTypes.ExecutionType.EMBEDDED_FUNCTION
)
```

### 4. Handling The Callback

When the execution is finished, your will receive the result within the `callbackTask`.

```solidity
function callbackTask(
        bytes calldata resultData, 
        string[] memory transcripts, 
        uint256 wtExecutionId, 
        uint8 status,
        string memory callbackMessageDetails
    ) external override onlywatchTower {
```

* **resultData:** The encoded result data from the execution.
* **transcripts:** Array of execution transcripts for verification.
* **wtExecutionId:**  The execution identifier.
* **status:** Execution status (0 = success, >0 = error).
* **callbackMessageDetails:** Additional details about the execution.


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