If you have replaced your web3 provider with Fortmatic provider, nothing needs to be changed for web3 ERC20 transaction to continue working. The following is an example on how to initiate an ERC20 token Approve.
Note that this ERC20 custom view will be displayed only on the mainnet, otherwise Generic Contract Call view will be displayed.
// Initialize providerimport Fortmatic from 'fortmatic';import Web3 from 'web3';​const fm = new Fortmatic('YOUR_API_KEY');window.web3 = new Web3(fm.getProvider());​// Get the contract ABI from compiled smart contract jsonconst erc20TokenContractAbi = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"tokens","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"to","type":"address"},{"name":"tokens","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"amount","type":"uint256"}],"name":"withdrawEther","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"_totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"tokenOwner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"acceptOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"a","type":"uint256"},{"name":"b","type":"uint256"}],"name":"safeSub","outputs":[{"name":"c","type":"uint256"}],"payable":false,"stateMutability":"pure","type":"function"},{"constant":false,"inputs":[{"name":"to","type":"address"},{"name":"tokens","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"a","type":"uint256"},{"name":"b","type":"uint256"}],"name":"safeDiv","outputs":[{"name":"c","type":"uint256"}],"payable":false,"stateMutability":"pure","type":"function"},{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"tokens","type":"uint256"},{"name":"data","type":"bytes"}],"name":"approveAndCall","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"a","type":"uint256"},{"name":"b","type":"uint256"}],"name":"safeMul","outputs":[{"name":"c","type":"uint256"}],"payable":false,"stateMutability":"pure","type":"function"},{"constant":true,"inputs":[],"name":"newOwner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"tokenAddress","type":"address"},{"name":"tokens","type":"uint256"}],"name":"transferAnyERC20Token","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"tokenOwner","type":"address"},{"name":"spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"a","type":"uint256"},{"name":"b","type":"uint256"}],"name":"safeAdd","outputs":[{"name":"c","type":"uint256"}],"payable":false,"stateMutability":"pure","type":"function"},{"constant":false,"inputs":[{"name":"_newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"tokens","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"tokenOwner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"tokens","type":"uint256"}],"name":"Approval","type":"event"}];​// Create contract objectconst tokenContract = web3.eth.contract(erc20TokenContractAbi);​// Instantiate contractconst tokenContractInstance = tokenContract.at('0x8EBC7785b83506AaA295Bd9174e6A7Ad5681fb80');const toAddress = '0xE0cef4417a772512E6C95cEf366403839b0D6D6D';​// Calculate contract compatible value for approve with proper decimal points using BigNumberconst tokenDecimals = web3.toBigNumber(18);const tokenAmountToApprove = web3.toBigNumber(999000000000);const calculatedApproveValue = web3.toHex(tokenAmountToApprove.mul(web3.toBigNumber(10).pow(tokenDecimals)));​// Get user account wallet address firstweb3.eth.getAccounts(function(error, accounts) {if (error) throw error;// Send ERC20 transaction with web3tokenContractInstance.approve.sendTransaction(toAddress, calculatedApproveValue, {from: accounts[0]}, function(error, txnHash) {if (error) throw error;console.log(txnHash);});});
// Initialize providerimport Fortmatic from 'fortmatic';import Web3 from 'web3';​const fm = new Fortmatic('YOUR_API_KEY');window.web3 = new Web3(fm.getProvider());​// Get the contract ABI from compiled smart contract jsonconst erc20TokenContractAbi = 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Create contract objectconst tokenContractAddress = '0x8EBC7785b83506AaA295Bd9174e6A7Ad5681fb80';​// Instantiate contractconst tokenContract = new web3.eth.Contract(erc20TokenContractAbi, tokenContractAddress);const toAddress = '0xE0cef4417a772512E6C95cEf366403839b0D6D6D';​// Calculate contract compatible value for approve with proper decimal points using BigNumberconst tokenDecimals = web3.utils.toBN(18);const tokenAmountToApprove = web3.utils.toBN(999000000000);const calculatedApproveValue = web3.utils.toHex(tokenAmountToApprove.mul(web3.utils.toBN(10).pow(tokenDecimals)));​// Get user account wallet address firstweb3.eth.getAccounts().then((accounts) => {// Send ERC20 transaction with web3tokenContract.methods.approve(toAddress,calculatedApproveValue).send({from: accounts[0]}).once('transactionHash', (hash) => { console.log(hash); }).once('receipt', (receipt) => { console.log(receipt); });});