approve
approve
method can be used to approve required amount on root token.
approve is required in order to deposit amount on polygon chain.
const erc20RootToken = plasmaClient.erc20(<root token address>, true);
// approve 100 amount
const approveResult = await erc20Token.approve(100);
const txHash = await approveResult.getTransactionHash();
const txReceipt = await approveResult.getReceipt();