ethereum/solidity

const DOMAIN_TYPE = [
    {
        type: 'string',
        name: 'name'
    },
    {
        type: 'string',
        name: 'version'
    },
    {
        type: 'uint256',
        name: 'chainId'
    },
    {
        type: 'address',
        name: 'verifyingContract'
    }
];

const domainData = {
    name: 'Market721',
    version: '1',
    chainId: '1337',
    verifyingContract: '0x296564F6260b95f99F93fB347d456b7FC825771b'
};

const OrderTypes = {
    AssetType: [
        { name: 'assetClass', type: 'bytes4' },
        { name: 'data', type: 'bytes' }

    ],
    Asset: [
        { name: 'assetType', type: 'AssetType' },
        { name: 'value', type: 'uint256' }
    ],
    Order: [
        { name: 'maker', type: 'address' },
        { name: 'makeAsset', type: 'Asset' },
        { name: 'taker', type: 'address' },
        { name: 'takeAsset', type: 'Asset' }
    ]
};

const createTypeData = (domain, primaryType, message, types) => {
    return {
        types: { EIP712Domain: DOMAIN_TYPE, ...types },
        domain,
        primaryType,
        message
    };
};