ENGLISH:

• 1、Currently we setthe token allowance is set to the max amount. Change this to be safer so the user only approves just the amount needed.

  In the trySwap function, I adjusted the "MAXApproval" parameter to the number of tokens entered by the user in the front-end, using the "sellAmount" parameter in swapPriceJSON

  2、Show estimated gas in $

  First get "gasPrice" by using "getGasPrice" in Ethers:

  provider.getGasPrice()
  

  Then use Chainlink to get the "latestRoundData" data of ETH, in which the "answer" is the real-time price of ETH:

  const addr = "0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e"
  const priceFeed = new ethers.Contract(addr, aggregatorV3InterfaceABI, provider)
  priceFeed.latestRoundData()
      .then((roundData) => {
          ETHprice = roundData.answer.toString()/10e7// Do something with roundData
          console.log("Latest price", ETHprice)
      })
  

  Finally, multiply estimatedGas, gasPrice, and ETHprice to get the $ gasfee:

  ethers.utils.formatEther(swapPriceJSON.estimatedGas)*gasPrice.toString()*ETHprice 
  

After learning the basic syntax of js by myself, I successfully completed the transformation and upgrading of the basic code.

Answer ALL of these questions:

• Who are you, and what is your software development background?

  I'm axrid, I'm not a computer science major, I only know some basic Python and JS. I'm learning solidity now and want to work in web3 related work.

• Why did you want to complete this lesson?

  I taught myself the basic syntax of JS and wanted to consolidate what I learned in this lesson. So I built the code following the video tutorial and completed the challenge.

• When did you complete the project?

  I started the course on November 1 and finished it on November 6, with a total duration of about 5h.

• What technologies did you use?

  https://docs.alchemy.com/docs/how-to-build-a-token-swap-dapp-with-0x-api

  I followed the official tutorials to learn, mainly using JS and the related APIs of Chainlink, 0x, and Alchemy.

• What did you enjoy about the tutorial?

  Through learning and modifying the code, I understood the relationship between the front-end modules. I also understand that front-end and Solidity are equally important in Blockchain development.

• How do you think you can use this technology to build useful applications in the future? What are some specific example applications?

  This is a tutorial about DEX, and to be honest, I'm not going to build a new DEX. in this lesson I learned to get token price through Chainink and interact with Blockchain through Ethers. I plan to make some JS scripts related to Blockchain.

• Who would you recommend this project to?

  A friend of mine who has learned JS, C++, Python, maybe he can master this lesson easily.

• What is the Ethereum wallet address you would like to receive your PoK at?

  My address (I may delete the wallet address from this post when I mint nft):

  0xe62ef3e82127bb97e641b15e866798c827206762

• My smart contract code:

  https://github.com/a9team2333/roadtoweb3/tree/main/week9

• I completed the following two challenges:

  1、Currently we setthe token allowance is set to the max amount. Change this to be safer so the user only approves just the amount needed.

  In the trySwap function, I adjusted the "MAXApproval" parameter to the number of tokens entered by the user in the front-end, using the "sellAmount" parameter in swapPriceJSON

  2、Show estimated gas in $

  First get "gasPrice" by using "getGasPrice" in Ethers:

  provider.getGasPrice()
  

  Then use Chainlink to get the "latestRoundData" data of ETH, in which the "answer" is the real-time price of ETH:

  const addr = "0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e"
  const priceFeed = new ethers.Contract(addr, aggregatorV3InterfaceABI, provider)
  priceFeed.latestRoundData()
      .then((roundData) => {
          ETHprice = roundData.answer.toString()/10e7// Do something with roundData
          console.log("Latest price", ETHprice)
      })
  

  Finally, multiply estimatedGas, gasPrice, and ETHprice to get the $ gasfee:

  ethers.utils.formatEther(swapPriceJSON.estimatedGas)*gasPrice.toString()*ETHprice 
  

中文:

自学了js的基本语法后，顺利的完成了基础代码的改造提升。

answer ALL of these questions:

• Who are you, and what is your software development background?

  我是axrid，我不是计算机专业，只会一些基础的python和js。我现在正在学习solidity，想要从事web3相关的工作。

• Why did you want to complete this lesson?

  我自学了js的基本语法，想要在这一课里巩固所学内容。因此我按照视频教程搭建了code，并完成了挑战。

• When did you complete the project?

  我从11月1日开始学习，在11月6完成课程，总时长大概5h。

• What technologies did you use?

  https://docs.alchemy.com/docs/how-to-build-a-token-swap-dapp-with-0x-api

  我跟随官方教程进行学习，主要使用javascript，以及chainlink, 0x, alchemy

• What did you enjoy about the tutorial?

  通过对代码的学习和修改，我理解了前端各个文件之间的关系。也明白了blockchain行业里，前端和solidity同样重要

• How do you think you can use this technology to build useful applications in the future? What are some specific example applications?

  这是一个关于DEX的教程，老实说，我不会去搭建一个新的DEX。在这一课我学会了通过chainink获取token price，通过ethers与blockchain交互。我打算做一些与blockchain相关的js脚本。

• Who would you recommend this project to?

  我的一位朋友，他学过js、c++、python，也许他可以很轻松的掌握这一课

• What is the Ethereum wallet address you would like to receive your PoK at?

• My smart contract code:

  https://github.com/a9team2333/roadtoweb3/tree/main/week9

我完成了以下两个挑战

1、目前我们设置令牌限额设置为最大金额.更改此项以使其更安全，以便用户仅批准所需的金额。

{}在trySwap中，我把MAXApproval的参数调整为用户在前端中输入的token数量，借用了swapPriceJSON中的sellAmount参数

2、以 $ 为单位显示估计的气体

{}首先通过Ethers中的getGasPrice来获取gasPrice

provider.getGasPrice()

然后使用Chainlink来获取ETH的latestRoundData数据，里面的”answer”就是ETH的实时价格

const addr = "0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e"
const priceFeed = new ethers.Contract(addr, aggregatorV3InterfaceABI, provider)
priceFeed.latestRoundData()
    .then((roundData) => {
        ETHprice = roundData.answer.toString()/10e7// Do something with roundData
        console.log("Latest price", ETHprice)
    })

最终将estimatedGas、gasPrice、ETHprice相乘，得到以美元计价的gasfee

ethers.utils.formatEther(swapPriceJSON.estimatedGas)*gasPrice.toString()*ETHprice