```
{% endtab %}
{% tab title="JavaScript" %}
```javascript
signTypedDataV4Button.addEventListener('click', function (event) {
event.preventDefault();
const msgParams = JSON.stringify({
domain: {
// Defining the chain aka Rinkeby testnet or Ethereum Main Net
chainId: 1,
// Give a user friendly name to the specific contract you are signing for.
name: 'Ether Mail',
// If name isn't enough add verifying contract to make sure you are establishing contracts with the proper entity
verifyingContract: '0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC',
// Just let's you know the latest version. Definitely make sure the field name is correct.
version: '1',
},
// Defining the message signing data content.
message: {
/*
- Anything you want. Just a JSON Blob that encodes the data you want to send
- No required fields
- This is DApp Specific
- Be as explicit as possible when building out the message schema.
*/
contents: 'Hello, Bob!',
attachedMoneyInEth: 4.2,
from: {
name: 'Cow',
wallets: [
'0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826',
'0xDeaDbeefdEAdbeefdEadbEEFdeadbeEFdEaDbeeF',
],
},
to: [
{
name: 'Bob',
wallets: [
'0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB',
'0xB0BdaBea57B0BDABeA57b0bdABEA57b0BDabEa57',
'0xB0B0b0b0b0b0B000000000000000000000000000',
],
},
],
},
// Refers to the keys of the *types* object below.
primaryType: 'Mail',
types: {
// TODO: Clarify if EIP712Domain refers to the domain the contract is hosted on
EIP712Domain: [
{ name: 'name', type: 'string' },
{ name: 'version', type: 'string' },
{ name: 'chainId', type: 'uint256' },
{ name: 'verifyingContract', type: 'address' },
],
// Not an EIP712Domain definition
Group: [
{ name: 'name', type: 'string' },
{ name: 'members', type: 'Person[]' },
],
// Refer to PrimaryType
Mail: [
{ name: 'from', type: 'Person' },
{ name: 'to', type: 'Person[]' },
{ name: 'contents', type: 'string' },
],
// Not an EIP712Domain definition
Person: [
{ name: 'name', type: 'string' },
{ name: 'wallets', type: 'address[]' },
],
},
});
var from = web3.eth.accounts[0];
var params = [from, msgParams];
var method = 'eth_signTypedData_v4';
web3.currentProvider.sendAsync(
{
method,
params,
from,
},
function (err, result) {
if (err) return console.dir(err);
if (result.error) {
alert(result.error.message);
}
if (result.error) return console.error('ERROR', result);
console.log('TYPED SIGNED:' + JSON.stringify(result.result));
const recovered = sigUtil.recoverTypedSignature_v4({
data: JSON.parse(msgParams),
sig: result.result,
});
if (
ethUtil.toChecksumAddress(recovered) === ethUtil.toChecksumAddress(from)
) {
alert('Successfully recovered signer as ' + from);
} else {
alert(
'Failed to verify signer when comparing ' + result + ' to ' + from
);
}
}
);
});
```
{% endtab %}
{% endtabs %}