(Updated)开发者自己做了一个事后分析，比我讲的清晰多了，当然主要原因还是JS module依赖设计的复杂度https://medium.com/javascript-in-plain-english/is-promise-post-mortem-cab807f18dcc 在这一点上我很看好deno这个新工具。
——————————-
看到微信群里有人转关于“is-promise”更新导致的问题，公众号文章说的非常夸张，但又语焉不详，看了毫无头绪。于是看了些英文文章，做了点技术分析。
首先声明，因为水平不够理解不深，这篇文章并没有解释清楚问题的原因，只是说了一下我看到的现象，确保将来写类似代码的时候，心里有点谱。
“is-promise“有问题的版本更新是2.2.0，看了更新diff没发现什么明显问题。更新的目的主要是增加ES module风格的默认import。
首先得熟悉一下ES Module的import，还有commonjs的require。
先说一下ES6标准化的module，在浏览器中可以通过<script type=”module”>导入模块脚本，代码是这样的：”import xxx from ‘module-name’”。如果用CommonJS呢，就是“const package = require(‘module-name’)”。
在Nodejs v12之前使用的是commonjs，在v12的时候引入了ES Module的支持。在node中可以通过条件导入同时支持两种方式（麻烦！）https://nodejs.org/dist/latest-v12.x/docs/api/esm.html#esm_conditional_exports
在nodejs的官方文档中https://nodejs.org/dist/latest-v12.x/docs/api/esm.html#esm_dual_commonjs_es_module_packages 特意解释了双模式package的问题，其中特意提到了“Dual Package Hazard”（双Package风险），说实话这部分有些复杂，我也没有太理解。在后面提到了“Differences Between ES Modules and CommonJS“，其中第一条就是”Mandatory file extensions“，但是文档说的还是不清不楚的。
我们看一下is-promise的bug fix能理解更深一些。https://github.com/then/is-promise/commit/0b69f52ee73c9f6ad4480f02c9bccb14d2038656 可以看到主要就是对文件路径指定，变成使用”./xxx.js”方式。为什么原来有问题，现在就能fix，说实话我还是没看懂。我在本地做了一个极为简单的node js脚本文件，引入了is-promise 2.2.0版本，尝试了import和require两种方式，没发现有问题。我也尝试从bug report中找点线索，但是大多数都是说xxx有问题了，没有细节。我甚至到create-react-app中查找is-promise，根本就没有，简直是磕了。
先这样吧，等我理解更多了再更新此文。
另外在HN上关于这件事的讨论https://news.ycombinator.com/item?id=22979245 也是非常热烈，不过没人分析原因，要么吐槽，要么建议用npm指定版本方式（版本号不用^和～）。
《 “(又一个)一行代码导致的血案-“is-promise”问题的粗浅分析” 》 有 3 条评论
People of all age groups as we intend to publish news classified into General, Political, Crime, Sports, li9.in Entertainment, Education and World News.Our reporting team intends to publish the Education & Recruitment Update for all age groups and present the true picture of the recent events with the inside coverage. Our objective would be to cater the requirements.
ekhan.net
The Reserve Bank of India’s guidelines are followed by the national bank Indian Overseas Bank.How to Update/Register Your Cell Number with Indian Overseas Bank, The Reserve Bank of India’s guidelines are followed by the national bank Indian Overseas Bank. The bank has been providing its clients in the public banking sector with a wealth of convenient services and amenities. Indian Overseas Bank (IOB) Mobile Banking Registration, How to Update/Register Your Cell Number with Indian Overseas Bank, The Reserve Bank of India’s guidelines are followed by the national bank Indian Overseas Bank. ekhan.net The bank has been providing its clients in the public banking sector with a wealth of convenient services and amenities. Indian Overseas Bank (IOB) Mobile Banking Registration.
we are providing the pdf based on internet search according to past years old examination test and those question bank or study material download and shared based on the internet only.All the Users of the BoardModelPapers can use those boardmodelpaper.com sample papers or Previous Paper Pdf of class-wise study material and blueprint and any for reference purpose only and we are providing the pdf based on internet search according to past years old examination test and those question bank.