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As part of the quote, you usually receive a list of token requirements. These requirements can span across multiple chains and tokens. There are two types of requirements:
  • ERC-20 token approvals: used to pre-approve the tokens to the Permit2 contract
  • ETH wrapping: used to wrap the ether into WETH, to be compatible with the Permit2 contract
Here’s an example of token requirements: 
{
  "8453": {
    "0x4200000000000000000000000000000000000006": {
      "type": "approval",
      "amount": "102656447694688542",
      "spender": "0x000000000022d473030f116ddee9f6b43ac78ba3"
    },
    "0x0000000000000000000000000000000000000000": {
      "type": "wrap",
      "amount": "102656447694688542"
    }
  }
}
In this example:
  1. ETH must be wrapped on Base.
  2. WETH (from the first step) must be approved for the Permit2 contract on Base.

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ERC-20 Approvals

Approve a token
import {
  switchChain,
  writeContract,
} from "@wagmi/core";
import {
  maxUint256,
} from "viem";

await switchChain(wagmiConfig, { chainId: chain.id });

const hash = await writeContract(wagmiConfig, {
  address,
  abi: [
    {
      name: "approve",
      type: "function",
      stateMutability: "nonpayable",
      inputs: [
        { name: "spender", type: "address" },
        { name: "amount", type: "uint256" },
      ],
      outputs: [{ name: "", type: "bool" }],
    },
  ],
  functionName: "approve",
  args: [requirement.spender, maxUint256],
});
While it’s possible to approve the exact amount, we suggest using infinite approvals to the Permit2 contract to streamline future UX.

​
ETH Wrapping

Wrap ETH
import {
  switchChain,
  writeContract,
} from "@wagmi/core";
import {
  maxUint256,
} from "viem";

await switchChain(wagmiConfig, { chainId: chain.id });

const hash = await writeContract(wagmiConfig, {
  address,
  abi: [
    {
      name: "deposit",
      type: "function",
      stateMutability: "payable",
      inputs: [],
      outputs: [],
    },
  ],
  functionName: "deposit",
  value: requirement.amount,
});
Once you’ve fulfilled all the necessary requirements, you can move on to signing the intent.

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Next Steps

Signing

Learn how to sign an intent