Icon LinkSimulate Transactions

Simulating a transaction is a powerful feature that allows you to validate whether a given transaction meets its requirements without modifying the blockchain. It's a safe way to ensure that a transaction will behave as expected without spending any real resources.

You can use the simulate() method to test your transactions:

const { gasUsed } = await contract.functions
	.transfer(amountToTransfer, assetId, someAddress)
	.callParams({
	forward: [amountToForward, BaseAssetId],
	})
	.txParams({ gasPrice: 1, gasLimit: 10_000 })
	.simulate();
 
console.log('The gas used on this call was: ', gasUsed')

Simulating a transaction allows you to catch potential errors or issues before submitting the real transaction, making it a valuable tool for development and user interaction.

Icon LinkRead-only Calls Using simulate()

When interacting with a contract, you might want to execute a method that does not change the state of the blockchain—for example, reading a value from storage without modifying it.

In such cases, you can use the simulate() method:

const { value } = await contract.functions
	.echo_u8(15)
	.txParams({ gasLimit: 10_000 })
	.simulate();

Using simulate() for read-only calls or to test transactions provides a way to safely and efficiently access information from the blockchain or validate how a transaction would behave. It ensures that no changes will be made to the blockchain and no resources will be spent, making it a valuable tool for data retrieval and development.

Icon LinkWhen to use simulate() vs call()

simulate(): Suitable for both read-only calls and testing transactions that could modify the blockchain's state, this method allows you to safely validate how functions will behave without making changes. It's a robust validation, development, and data retrieval utility method, providing confidence in your transactions and interactions with the blockchain.

call(): Use this method when calling a function that modifies the blockchain's state, such as transferring funds or updating values. Remember that if you use call() on a contract method that changes the blockchain state, it will spend your resources.

It is worth noting that while call() can be used to execute read-only contract methods without spending resources, it's recommended to use simulate() for such calls. Using simulate() guarantees that no resources will be spent even if you accidentally execute a contract method that would typically change the blockchain. This additional safeguard makes simulate() preferable for read-only interactions.

Icon InfoCircle

Note: Although a simulate() call won't modify the blockchain's state and does not spend resources, the transaction must still meet its requirements to be considered valid.