Ashish Patel: Notes

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Proxy Pattern

A proxy is an object that has the same interface as another object and is used in place of that other object. It provides a surrogate or placeholder for another object to control access to it. It intends to add a wrapper and delegation to protect the real component from undue complexity.

Use cases

// External API Service
function CryptocurrencyAPI() {
  this.getValue = function (coin) {
    console.log('Calling External API...')
    switch (coin) {
      case 'Bitcoin':
        return '$8,500'
      case 'Litecoin':
        return '$50'
      case 'Ethereum':
        return '$175'
      default:
        return 'NA'
    }
  }
}

function CryptocurrencyProxy() {
  this.api = new CryptocurrencyAPI()
  this.cache = {}

  this.getValue = function (coin) {
    if (this.cache[coin] == null) {
      this.cache[coin] = this.api.getValue(coin)
    }
    return this.cache[coin]
  }
}

const proxy = new CryptocurrencyProxy()
console.log(proxy.getValue('Bitcoin'))
console.log(proxy.getValue('Litecoin'))

Created 2019-01-23T11:45:03+05:18, updated 2020-08-23T10:52:17+05:18 · History · Edit