CODE EXAMPLE FOR JAVASCRIPT

chain id

Ethereum :"0x1",
Local Chain :"0x539",
Ropsten Testnet :"0x3",
Rinkeby Testnet :"0x4",
Kovan Testnet :"0x2a",
Goerli Testnet :"0x5",
Binance :"0x38",
Smart Chain Testnet :"0x61",
Polygon :"0x89",
Mumbai :"0x13881",
Avalanche" : "0xa86a",