Method async executeApproval ( params : ApproveTokenParams ): Promise <{ transactionHash : string ; explorerUrl : string ; }>
Executes a token approval transaction, allowing the DEX contract to spend a specified amount of tokens on behalf of the user. This is required before executing swaps for ERC-20 tokens.
Parameters params
ApproveTokenParams
required
Approval request parameters Chain identifier (e.g., “1” for Ethereum)
Contract address of the token to approve
Amount to approve (in token’s smallest unit). Use a large number like “115792089237316195423570985008687907853269984665640564039457584007913129639935” for unlimited approval.
Response Transaction hash of the approval transaction
Block explorer URL for the approval transaction
Configuration Requirements Requires EVM wallet configuration:
const client = new OKXClient ({ apiKey: 'your-api-key' , secretKey: 'your-secret-key' , apiPassphrase: 'your-passphrase' , projectId: 'your-project-id' , evm: { wallet: evmWallet // EVMWallet instance } });
Example import { OKXClient } from '@okxweb3/okx-api' ; import { EVMWallet } from '@okxweb3/okx-api/evm' ; const evmWallet = new EVMWallet ( 'your-private-key' ); const client = new OKXClient ({ apiKey: 'your-api-key' , secretKey: 'your-secret-key' , apiPassphrase: 'your-passphrase' , projectId: 'your-project-id' , evm: { wallet: evmWallet } }); try { // Approve USDC for trading const result = await client . dex . executeApproval ({ chainIndex: '1' , tokenContractAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48' , approveAmount: '115792089237316195423570985008687907853269984665640564039457584007913129639935' // Unlimited }); console . log ( 'Approval successful!' ); console . log ( 'Transaction:' , result . transactionHash ); console . log ( 'Explorer:' , result . explorerUrl ); } catch ( error ) { console . error ( 'Approval failed:' , error . message ); }
Response Example { "transactionHash" : "0xabcdef1234567890..." , "explorerUrl" : "https://web3.okx.com/explorer/ethereum/tx/0xabcdef1234567890..." }
Workflow
Retrieves network configuration for the specified chain
Fetches the DEX approval contract address using getChainData()
Creates an approval executor using SwapExecutorFactory
Executes the approval transaction with the specified amount
Returns the transaction hash and explorer URL
Already Approved Tokens If the token is already approved for the requested amount or more, the method returns:
{ "transactionHash" : "" , "explorerUrl" : "" , "alreadyApproved" : true , "message" : "Token already approved for the requested amount" }
Approval Amounts Unlimited Approval For maximum convenience (but less security):
const MAX_UINT256 = '115792089237316195423570985008687907853269984665640564039457584007913129639935' ; await client . dex . executeApproval ({ chainIndex: '1' , tokenContractAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48' , approveAmount: MAX_UINT256 });
Exact Amount Approval For better security, approve only the amount needed:
await client . dex . executeApproval ({ chainIndex: '1' , tokenContractAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48' , approveAmount: '1000000000' // 1000 USDC (6 decimals) });
Error Handling try { const result = await client . dex . executeApproval ( params ); } catch ( error ) { if ( error . message . includes ( 'No dex contract address' )) { // Chain not supported or configuration issue } else if ( error . message . includes ( 'wallet' )) { // EVM wallet not configured } else { // Other errors (network, gas, etc.) } }
Notes
Only required for ERC-20 tokens (not needed for native tokens like ETH)
Approval is chain-specific and token-specific
Approval persists until revoked or a new approval is made
Consider security implications of unlimited approvals