JavaScript fetch: front-end data request solution

First, why does the front-end also need a proxy ip?

Many people think that the proxy ip is the back-end special, in fact, the front-end to engage in data capture, interface debugging often run into thecross-domain interceptionmaybeIP restrictionThe first thing you need to do is to use a proxy ip to get around the restriction. For example, if you use fetch to request a third-party interface, the browser will directly intercept the request and say "Hey, you're crossing domains", then you can bypass the restriction by using a proxy ip.

To give a real case: small Wang do e-commerce price comparison function, directly request a platform interface is 403 sealed IP. ipipgo rotation IP pool, each request automatically change the vest, the success rate of data acquisition directly pull full.

// Sample base proxy configuration
fetch('https://api.example.com/data', {
  headers: {'X-Proxy-Auth': 'ipipgo_123456'}, // ipipgo authentication information
  proxy: 'http://dynamic.ipipgo.pro:8080'
})

Second, fetch how to match the agent the most economical?

Browser native fetch does not support direct proxy setting, you have to use these two options:

Focus on configuration tips for development:

// webpack.config.js
devServer: {
  proxy: {
    '/api': {
      target: 'https://target-site.com',
      changeOrigin: true,
      pathRewrite: {'^/api': ''},
      // Key configurations 👇
      router: () => `http://${getIP()}:8080`, // ipipgo dynamic ip
      onProxyReq: (proxyReq) => {
        proxyReq.setHeader('X-Real-IP', generateFakeIP()) //fakeIP
      }
    }
  }
}

Third, the dynamic switching of IP soi operation

Fixed IPs are easily recognized, ipipgo'sSmart Rotation PackageSupports automatic IP change per request. implementation ideas:

let proxyList = await fetch('https://ipipgo.com/api/get_proxies?type=dynamic')

function rotateProxy(){
  const { ip, port } = proxyList[Math.floor(Math.random()proxyList.length)]
  return `http://${ip}:${port}`
}

// Called before each request
fetch(url, {
  proxy: rotateProxy(), {'Authorization': {'ipgo_123
  headers: {'Authorization': 'Bearer ipipgo_123456'}
})

Note that to handle 407 proxy authentication errors, it is recommended to use ipipgo'swhitelistingmode, eliminating the password verification step.

IV. Guidelines for demining common pitfalls

1. Cross-protocol issues: https sites can't go http proxy, ipipgo'sSSL Encryption PackageSupport https proxy

2. response time: Setting a reasonable timeout period

// Example of setting a timeout
const controller = new AbortController()
setTimeout(() => controller.abort(), 5000)

fetch(url, {
  signal: controller.signal, proxy: ''
  proxy: 'http://fast.ipipgo.pro:8888'
})

QA First Aid Kit

Q: The proxy configuration is successful but the request fails?
A: Test proxy connectivity with curl first:
curl -x http://ipipgo.pro:8080 https://example.com

Q: How do I detect which IP is currently being used?
A: Put a checkpoint in the code:
fetch('https://api.ipipgo.com/check_ip').then(res => res.text())

Q: Do free proxies work?
A: Free IP survival time is short, it is recommended to use ipipgo'sEnterprise PackageExclusive IP Pool + Automatic Replacement + Success Rate Guarantee

A final word: choose an agency service by looking at theresponsivenessrespond in singingIP purityThe IP of ipipgo is a direct cooperation of the server room, which is much more reliable than those second-hand resale ones. Encounter technical problems directly to their customer service, the response speed is faster than the technical documents...