How to Check Token Approval Allowance for DEX Transactions

Understanding Token Approval Allowance

Note:
Currently, OKX DEX has discontinued its interface for querying trading authorization allowances. Users must employ third-party methods to check these values. Below are recommended approaches.

Third-Party Query Methods

Example: ETH Chain Implementation

Here’s a step-by-step guide to query token approval allowances using JavaScript:

Prerequisites

• Connect to an Ethereum Node: Use libraries like web3.js to link to an Ethereum node (HTTP/WebSocket endpoint).
• Token Contract Instance: Instantiate the token contract using its address and ABI.
• Query Allowance: Call the allowance function with the owner’s address and the spender’s address (e.g., DEX approval address).

Code Demo

const { Web3 } = require('web3');
const web3 = new Web3('https://xxxxx'); // Node endpoint
const tokenAddress = '0xxxxxxxxx'; // Token contract address
const ownerAddress = '0xxxxxxxx'; // User address
const spenderAddress = '0x40aa958dd87fc8305b97f2ba922cddca374bcd7f'; // DEX approval address

const tokenABI = [{
  "constant": true,
  "inputs": [
    { "name": "_owner", "type": "address" },
    { "name": "_spender", "type": "address" }
  ],
  "name": "allowance",
  "outputs": [{ "name": "", "type": "uint256" }],
  "stateMutability": "view",
  "type": "function"
}];

const tokenContract = new web3.eth.Contract(tokenABI, tokenAddress);

async function getAllowance(ownerAddress, spenderAddress) {
  try {
    const allowance = await tokenContract.methods.allowance(ownerAddress, spenderAddress).call();
    console.log(`Allowance for ${ownerAddress} to ${spenderAddress}: ${allowance}`);
  } catch (error) {
    console.error('Failed to query allowance:', error);
  }
}
getAllowance(ownerAddress, spenderAddress);

Key Notes

• Spender Address: Refer to the DEX Limit Order API for the correct dexTokenApproveAddress.
• Adjustments: Replace placeholder values (e.g., https://xxxxx, 0xxxxxxxxx) with actual contract details.

👉 Maximize your DEX trading efficiency with seamless token approval checks.

FAQs

1. Why can’t I query allowances directly via OKX DEX?

OKX has deprecated this feature to streamline services. Users must now use third-party tools or custom scripts.

2. How do I find the spender address for other blockchains?

Check the respective blockchain’s DEX documentation or API responses for the dexTokenApproveAddress.

3. What if the allowance returns zero?

Ensure the token contract is approved for the spender address. Use approve() function if necessary.

👉 Explore advanced Web3 API integrations for broader functionality.

Best Practices

• Security: Verify contract addresses and ABI from official sources.
• Gas Fees: Allowance queries are read-only and don’t incur gas costs.
• Scalability: Batch queries for multiple tokens to optimize performance.