Flow Object.values(…)
JavaScript typing utilities, like Flow and TypeScript, have become popular in JavaScript apps of all sizes. As I mentioned in our Script & Style Show typing podcast, typing is a great way to implicitly implement documentation and validation. Flow isn't always easy to perfect, however, and Object.values was a pain point for me.
When using Flow, Object.values could trigger the following error:
Cannot call Object.values(…).map with function bound to callbackfn because property {prop} is missing in mixed [1] in the first argument.
The reason for this error is that Object.values() could return any value type. One way to get past this annoyance is to use the following:
...(Object.values(whatever): any)
Using an any type is never ideal but providing a type with Object.values will help satisfy Flow. In the end, it does make sense that Object.values isn't trusted, because anything could be returned, but having to use any is a tough pill to swallow for type lovers!
![Write Better JavaScript with Promises]()
You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...
![Facebook Open Graph META Tags]()
It's no secret that Facebook has become a major traffic driver for all types of websites. Nowadays even large corporations steer consumers toward their Facebook pages instead of the corporate websites directly. And of course there are Facebook "Like" and "Recommend" widgets on every website. One...
![CSS Scoped Styles]()
There are plenty of awesome new attributes we've gotten during the HTML5 revolution: placeholder, download, hidden, and more. Each of these attributes provides us a different level of control over an element on the page, but there's a new element attribute that allows...
![Web Notifications API]()
Every UI framework has the same set of widgets which have become almost essential to modern sites: modals, tooltips, button varieties, and notifications. One problem I find is each site having their own widget colors, styles, and more -- users don't get a consistent experience. Apparently the...
This saves a lot of time of debugging hours. Thank you for the post.