How to structure input parameter to object in JS-CodePudding

I have a simple Express API here. When the user submits the chain param I want to convert the parameter to an object. Depending on the input the object will have different values Right now I just have a bunch of if statements stacked

Is there a better practice solution to implement this as this is quite clunky?

app.get('/gettokens/:chain/:address', async(req, res) => {
    const address = req.params.address;
    let chain = req.params.chain;

    if (chain == 'bsc') {
        chain = {
            moralis: 'bsc',
            coingecko: 'binance-smart-chain'
        }
    }

    if (chain == 'eth') {
        chain = {
            moralis: 'eth',
            coingecko: 'ethereum'
        }
    }

    if (chain == 'avax') {
        chain = {
            moralis: 'avalanche',
            coingecko: 'avalanche'
        }
    }

    if (chain == 'matic') {
        chain = {
            moralis: 'matic',
            coingecko: 'polygon-pos'
        }
    }

CodePudding user response：

You can try using a constant object

const chainDef = {
     bsc: {  
                 moralis: ‘bsc’,
                 coingecko: ‘binance-smart-chain’
       } ,
    …
}

// you should validate `req.params.chain` before doing this
const chain = chainDef[req.params.chain]

Hope this helps!

CodePudding user response：

You can use some configuration object to handle it

like this

const config = {
  bsc: {
    moralis: 'bsc',
    coingecko: 'binance-smart-chain'
  },
  eth: {
    moralis: 'eth',
    coingecko: 'ethereum'
  },
  avax: {
    moralis: 'avalanche',
    coingecko: 'avalanche'
  },
  matic: {
    moralis: 'matic',
    coingecko: 'polygon-pos'
  }

}


const fallback = {
    moralis: 'something',
    coingecko: 'something'
  }
  
  
  const getChain = (key) => config[key] || fallback
  
  console.log(getChain('matic'))
  console.log(getChain('not defined'))

CodePudding user response：

You could define an object with all your different values and use the expected req.params.chain as keys:

const ChainObjs = {
  bsc: {
    moralis: 'bsc',
    coingecko: 'binance-smart-chain'
  },
  eth: {
    moralis: 'eth',
    coingecko: 'ethereum'
  },
  ...
}

And then you can get the correct value like this

app.get('/gettokens/:chain/:address', async(req, res) => {
  let chain = ChainObjs[req.params.chain]
})

CodePudding user response：

As david suggested, you can use a switch statement:

/*
app.get('/gettokens/:chain/:address', async(req, res) => {
    const address = req.params.address;
    let chain = splitChain(req.params.chain); 
}
*/

function splitChain(value) {
  let coingecko
  switch (value) {
    case 'bsc':
      coingecko = 'binance-smart-chain'
      break;
    case 'eth':
      coingecko = 'ethereum'
      break;
    case 'avax':
      coingecko = 'avalanche'
      break;
    case 'matic':
      coingecko = 'polygon-pos'
      break;
    default:
      coingecko = null
      break;
  }
  return {
    moralis: value,
    coingecko: coingecko
  }
}

console.log(splitChain('bsc'))
console.log(splitChain('eth'))
console.log(splitChain('avax'))
console.log(splitChain('wrong-value'))