Swicthing and adding network programatically on metamask

switch.js

  async function switchN(){

    const provider = window.ethereum;
    const binanceTestChainId = '0x61';
    
if(!provider){
  
    console.log("Metamask is not installed, please install!");
}else{
  
  const chainId = await provider.request({ method: 'eth_chainId' });
  
  if(chainId === binanceTestChainId){
    
  console.log("Bravo!, you are on the correct network");
}else{
  
console.log("oulalal, switch to the correct network");
try {
  
    await provider.request({
    method: 'wallet_switchEthereumChain',
    params: [{ chainId: binanceTestChainId}],
  });
  console.log("You have succefully switched to Binance Test network")
  
} catch (switchError) {
  // This error code indicates that the chain has not been added to MetaMask.
  if (switchError.code === 4902) {
   console.log("This network is not available in your metamask, please add it")
   try {
      await provider.request({
        method: 'wallet_addEthereumChain',
        params: [
        { chainId: '0x61', 
          chainName:'Smart Chain - Testnet',
          rpcUrls:['https://data-seed-prebsc-1-s1.binance.org:8545'],
          blockExplorerUrls:['https://testnet.bscscan.com'],
          nativeCurrency: {
        symbol:'BNB', // 2-6 characters long
    decimals: 18
      }
          
          }],
      });
    } catch (addError) {
      // handle "add" error
      console.log(addError);
    }
  }

}
}
  }