@0xpolygonid/js-sdk/dist/node/esm/storage/blockchain/erc20-helper.js

SDK to work with Polygon ID

import { Contract } from 'ethers';
import permitAbi from './abi/ERC20Permit.json';
import erc20Abi from './abi/ERC20.json';
/**
 * @beta
 * getPermitSignature is a function to create EIP712 Permit signature
 * @param {Signer} signer - User who owns the tokens
 * @param {string} tokenAddress - EIP-2612 contract address
 * @param {string} spender -  The contract address that will spend tokens
 * @param {bigint} value - Amount of tokens to approve
 * @param {number} deadline - Timestamp when the permit expires
 * @returns {Promise<PaymentRequestMessage>}
 */
export async function getPermitSignature(signer, tokenAddress, spender, value, deadline) {
    const erc20PermitContract = new Contract(tokenAddress, permitAbi, signer);
    const nonce = await erc20PermitContract.nonces(await signer.getAddress());
    const domainData = await erc20PermitContract.eip712Domain();
    const domain = {
        name: domainData[1],
        version: domainData[2],
        chainId: domainData[3],
        verifyingContract: tokenAddress
    };
    const types = {
        Permit: [
            { name: 'owner', type: 'address' },
            { name: 'spender', type: 'address' },
            { name: 'value', type: 'uint256' },
            { name: 'nonce', type: 'uint256' },
            { name: 'deadline', type: 'uint256' }
        ]
    };
    const message = {
        owner: await signer.getAddress(),
        spender: spender,
        value: value,
        nonce: nonce,
        deadline: deadline
    };
    return signer.signTypedData(domain, types, message);
}
/**
 * @beta
 * getERC20Decimals is a function to retrieve the number of decimals of an ERC20 token
 * @param {string} tokenAddress - Token address
 * @param {ethers.ContractRunner} runner - Contract runner
 */
export async function getERC20Decimals(tokenAddress, runner) {
    const erc20Contract = new Contract(tokenAddress, erc20Abi, runner);
    return erc20Contract.decimals();
}