checkAndApprove()
function checkAndApprove(client, props): Promise<undefined | `0x${string}`>Checks if the current allowance for a given spender is less than the specified amount and approves the spender to transfer the specified amount of tokens from the given account if necessary.
If the address is not the zero address and the existing allowance is less than the required amount,
it calls the approve function of the specified ERC20 contract to approve the given amount.
If the address is the zero address or the existing allowance is sufficient, it does nothing and returns undefined.
Parameters
| Parameter | Type | Description |
|---|---|---|
client | WriteClient | WriteClient The write client to use. |
props | ERC20CheckAndApproveProps | ERC20CheckAndApproveProps The properties containing the address, spender, amount, and account. |
type ERC20CheckAndApproveProps: WriteContractBaseProps & {
address: Address;
spender: Address;
amount: bigint;
};Returns
Promise<undefined | `0x${string}`>
The result of the approve call if approval is necessary, otherwise undefined.
Examples
erc20.ts
// for default amount
import { erc20 } from '@solio/core';
import { createWalletClient, custom } from 'viem';
import { sepolia } from 'viem/chains';
const writeClient = createWalletClient({
chain: sepolia,
transport: custom(window.ethereum),
});
const hash = await checkAndApprove(writeClient, {
address: '0x...', // ERC20 contract address
spender: '0x...'
});
console.log(hash);erc20.ts
// for custom amount (100wei)
import { erc20 } from '@solio/core';
import { createWalletClient, custom } from 'viem';
import { sepolia } from 'viem/chains';
const writeClient = createWalletClient({
chain: sepolia,
transport: custom(window.ethereum),
});
const hash = await checkAndApprove(writeClient, {
address: '0x...', // ERC20 contract address
spender: '0x...',
amount: 100n // 100 wei
});
console.log(hash);