How to Use a Signer in Ethers.js?

Web3 solutions have emerged as the next generation of software applications with a new approach to data storage and exchange. The promising value advantages of web3 include transparency, decentralization, and ubiquitous connectivity. For example, non-fungible tokens and metaverse platforms could transform the quality of digital experiences. However, it is important to learn about what happens behind the scenes of web3 applications, especially if you are aspiring to become a web3 developer. Among the many components involved in creating smart contracts, the ethers signer is a prominent tool for blockchain developers. When you develop interfaces for smart contracts, you would need signers and providers. Providers are the Ethereum node connection which helps in reading data from its state. Signers in ethers.js library are also Ethereum node connections that help you in writing data to a blockchain network.

The importance of a signer in ethers.js library reflects in its ability to write functions in smart contracts and transferring ETH between two accounts. On top of it, a signer could also do everything that a provider could, thereby ensuring a double advantage for developers. The following post offers you a detailed introduction to signers and how to use them in ethers.js.

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Understanding Ethers.js

Ethers.js is a JavaScript library that offers a comprehensive instrument for interactions with the Ethereum blockchain and the related ecosystem. Before you find the answers to “What is signer in ethers?” you should understand the significance of ethers.js library. After its launch in 2015, ethers.js has climbed the ranks of popularity among web3 developers as a powerful and trusted general-purpose library. Here are some of the most notable features of ethers.js library. 

• Safe storage of private keys in the client. 
• Importing and exporting HD wallets and BIP-39 mnemonic phrases.
• Lightweight size with compressed size being 88KB and uncompressed size at 284KB.
• Support for connection with Ethereum nodes through JSON-RPC, Metamask, Alchemy, and other web3 tools.
• Massive collection of test cases, which go through continuous maintenance and updates.
• The meta-classes in ethers.js library could help in creating JavaScript objects from contract ABIs.
• Comprehensive support for a diverse range of Ethereum uses cases and facility for extensive documentation.

The features of ethers.js library show that it is a powerful tool for improving productivity of web3 developers. In addition, you can also find tools like signers for improving productivity. As one of the notable blocks of ethers.js library, signers could offer better prospects to web3 developers for improving their workflows.

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Definition of Signers

Signers are the abstractions of Ethereum accounts, which can help in signing transactions and messages. Signers could also transfer signed transactions to Ethereum blockchain network for executing operations to change state. Another important aspect in the definition of a signer in ethers.js library is the availability of operations according to concerned sub-class. For instance, signers from Metamask wallet could send transactions alongside signing messages without signing or broadcasting transactions. The common types of signers you can come across in ethers.js include the following,

• JsonRpcSigner is one of the signers obtained through getSigner and stays connected with a JSON-RPC provider such as Infura.
• Another notable ethers signer example is a wallet. The wallet class has awareness about the associated private key alongside ensuring flexibility for executing the associated operations. 

Signers could access a private key and provide access for secure off-chain signing of messages and transactions while interacting with a blockchain network. The applications of signers in ethers.js also help you in verifying ownership of a specific account. It can help in sending transactions to the blockchain from the concerned account.

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Use Cases of Signer in Ethers.js 

The definition of signers provides a clear glimpse into their significance in the ethers.js library. How could you find an effective approach for leveraging signers using ethers.js in web3 development? The four notable use cases of signers include, 

• Wallet use case of signer helps in creating a new wallet with the help of a private key through identification of wallet owner. You can use the command ethers.Wallet for accessing the wallet use case. 
• Signers could also help you in retrieving the balance in a user’s wallet with the help of ‘signer.getBalance’ command. 
• Signing is an obvious use case of ethers signer which you can access through signer.signTransaction for signing a transaction to ensure confirmation of ownership through a specific wallet address. 
• Developers can also utilize ‘signer.resolveName’ command for signing a transaction to facilitate confirmation of ownership through a particular wallet address.

In addition, you can also find many other use cases of signers in ethers.js for web3 development.

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Important Components in the Working of Signer

The next crucial highlight in an introduction to signers is the outline of best practices for using signers. Signer classes are abstract in nature and cannot be instantiated directly. Therefore, you have to utilize a concrete sub-class such as JsonRpcSigner, Wallet, and VoidSigner. Here are some of the notable steps that can help you start using signers.

Sub-classes should implement the command “signer.connect(provider) ⇒ Signer”. However, sub-classes could also return an error in event of a lack of support for modifying providers.

The “signer.getAddress( ) ⇒ Promise< string< Address > >”  command is another important addition to methods for instantiation of signers using the recommended experts. Such a command could help in returning a promise to resolve the specified account address. It serves as a promise for ensuring the flexibility of designing signers based on asynchronous sources like hardware wallets. 

In addition, sub-classes should also implement the command such as “Signer.isSigner( object ) ⇒ boolean”. It would return true only when the object qualifies as a signer.

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What Are The Blockchain Methods in Signers?

The utilities of a signer in ethers.js also involve blockchain methods. Here are the notable commands which help in using blockchain methods with signers in ethers.js library. 

The following command could help you in retrieving the wallet balance at blockRam.

signer.getBalance( [ blockRam = "latest" ] ) ⇒ Promise< BigNumber >

Developers can use the command “signer.getGasPrice( ) ⇒ Promise< BigNumber >” to return current gas price.

The responses to “What is signer in ethers?” would also focus on blockchain methods for returning chain ID for the connected wallet. The command for using such a blockchain method is

signer.getChainId( ) ⇒ Promise< number >

Signers also leverage blockchain methods for returning the results of calling by utilizing the transactionRequest, while utilizing an account address from the field.

signer.call( transactionRequest ) ⇒ Promise< string< DataHexString > >

Developers can utilize blockchain method ‘getTransactionCount’ to return the total count of transactions transferred from an account. Here is an example of implementing such blockchain methods in signers using a simple command.

signer.getTransactionCount( [ blockTag = "latest" ] ) ⇒ Promise< number >

The following example shows you another functionality of blockchain methods in signers for returning the address related to ensName.

signer.resolveName( ensName ) ⇒ Promise< string< Address > >

You can also use the ethers signer example for blockchain method to retrieve the outcome of cost estimates for sending concerned transactionRequest with the following command.

signer.estimateGas( transactionRequest ) ⇒ Promise< BigNumber >

Developers could also leverage blockchain methods for returning the outcome of calls by utilizing the transactionRequest, such as the following example,

signer.call( transactionRequest ) ⇒ Promise< string< DataHexString > >

What is the Process of Signing using Signers in Ethers.js?

The process for utilizing ethers signer in signing transactions starts with the following command.

signer.signMessage( message ) ⇒ Promise< string< RawSignature > > 

The command returns the promise for resolving to a specific ‘Raw Signature’ associated with the ‘message.’ Signed messages are noted for the prefix “\x19Ethereum Signed Message:\n” alongside the message length by utilizing methods like ‘hashMessage’ method. It could ensure EIP-191 compliance. The prefix is an important requirement for creating a similar hash during recovery of a Solidity address. Sub-classes have to implement this and could also throw in cases of an incompatible message, such as a wallet for meta-transactions or a contract-based wallet. 

The next method for implementing signers using simple commands can help in returning a promise for resolving specific signed transactions associated with the ‘transactionRequest.’ On top of it, the method does not have any role in populating the fields that are missing. Sub-classes are required to follow the method, although they could throw in the lack of support for transaction signing. It is a mandatory requirement for ensuring security in the case of multiple clients. 

Another method for using signers in ethers.js helps in populating the ‘transactionRequest’ featuring missing fields by utilizing ‘populateTransaction.’ The following method also returns the promise to resolve the transaction.

signer.sendTransaction( transactionRequest ) ⇒ Promise< TransactionResponse >

This method of using signer in ethers.js is mandatory for sub-classes, which could also throw the method in the lack of support for sending transactions. For example, scenarios that involve VoidSigner, an offline wallet, or a lack of connection to providers.      

The following example for using signers in ethers.js shows a method for signing a typed data value by using the ‘types’ data structure in the case of the concerned ‘domain’ by leveraging the EIP-712 standard. 

signer._signTypedData( domain , types , value ) ⇒ Promise< string< RawSignature > >

Significance of Sub-Classes

You must be wondering about the role of sub-classes in the working of ethers signer for web3 development. Another question about sub-classes would be ‘why they have to implement the methods’ and how they work. Developers must ensure immutability of the crucial traits of a signer. It is important to note that Ethereum is asynchronous in nature, and transactions on Ethereum involve valuable assets. 

Therefore, developers should ensure that properties like ‘address’ and ‘provider’ have to be static across the complete life cycle of concerned signer. As a result, they could ensure safeguards against complicated threats and vulnerabilities. Interestingly, all the libraries and classes follow a similar assumption.    

The highlights of sub-classes in signers would also focus on the need for sub-classes to extend signers. In addition, it is also mandatory for sub-classes to call the super () function.

Another sub-class you can use in signers is the following example,

signer.checkTransaction( transactionRequest ) ⇒ TransactionRequest

The sub-class would not require overriding. At the same time, it could be required to facilitate custom behavior with sub-classes. The application of this sub-class in a guide on ‘What is signer in ethers?’ would show you how it could return the copy of ‘transactionRequest.’ You can also access required properties by using functions such as ‘populateTransaction,’ ‘call,’ or ‘estimateGas’. 

The sub-class could also return an error in the event of specifying unknown keys. Default implementations of the sub-class check for existence of valid properties related to TransactionRequest. It also adds ‘from’ in the transaction in the lack of valid TransactionRequest traits. At the same time, the ‘from’ field should be verified as similar to the address of the signer.

The next popular addition among the sub-classes in signers is the following example,

signer.populateTransaction( transactionRequest ) ⇒ Promise< TransactionRequest >

The unique highlight of this sub-class is that it does not require overriding. However, it is an important requirement for offering custom behavior in the sub-classes. The sub-class could return a copy of ‘transactionRequest,’ and you have to follow the procedure similar to ‘checkTransaction.’ 

You should also fill in the required properties for transaction transfer. The outcomes should ensure the resolution of all promises, and ‘resolveProperties’ utility function could help in achieving the objective. Default implementation of the sub-class works by calling ‘checkTransaction’ function alongside resolving to it in the case of ENS names.

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Conclusion 

The comprehensive review of ethers signer example methods and their significance shows that it is a crucial tool for developers. Signers are a crucial element in the functionalities of ethers.js as they help in writing data for smart contracts. It is an essential requirement in the ethers.js library for adding new functionalities to dApps with simple methods. 

The discussion also showed the effective ways for using signers in ethers.js for web3 development. For instance, the use cases of Signer provided a glimpse of its functionalities for creating wallets and retrieving wallet balances. You can start learning more about other web3 development tools and the importance of ethers.js for blockchain developers right now.