Thoughts on building & testing JavaScript, CSS, HTML, et al… (formerly dfkaye.github.io)
In a react/redux application:
jsx
capture its state by setting its vDom state with { [name]: !this.state.checked }
in a switch statement
unit tests are jest snapshot diffs
in typescript
className="bootstrap" or className={style.injection}
incompatible
Making simple things hard in the front end again.
Earlier this year a colleague was tasked with modifying an application that defined a very large object (i.e., containing 20+ properties). The troubling part was that the object was entirely defined twice, first in an if-block, then in an else-block, all 20+ properties spelled out in each. That made the differences between the definitions difficult to detect just by scanning.
Continue reading “Two object definition refactorings from 2017”
I found a rounding bug in Number().toFixed() in every JavaScript environment I’ve tried (Chrome, Firefox, Internet Explorer, Brave, and Node.js). The fix is surprisingly simple. Read on…
Continue reading “Number().toFixed() rounding errors: broken but fixable”
Given this format, '2017-05-01', I want the date of May 1, 2017.
Continue reading “Why input string format matters for JavaScript (and moment.js) dates”
User interface components in general are built with an expected user behavior. We used the jQuery-UI datepicker, to save time, but in an unusual way, which cost us a lot of time discovering what we’d missed. We re-learned a key insight, namely, month and year are navigation, not selection controls.
Continue reading “Using only Month and Year in jQueryUI Datepickers”
[ originally posted 12 Feb 2013 ]
Note: this post acts as justification for my Constructor kata on github. It’s really a re-post for posterity, as 1) I thought it worth preserving a specimen of my former thinking, because 2) I think far less often in the constructor/super inheritance pattern in JavaScript than I did even a year ago (i.e, summer of 2014).
[ original gist 28 March 2013 ]
“If there are no tests, it does not work,” a former colleague said, who could have added, “whether your code or someone else’s.”
I’m not the first to say it but it needs re-stating: 3rd-party libraries are no guarantee that your code continues to behave as expected.
If one of the duties of your work is making sure you’re not introducing bloat or cruft or inefficiencies or bugs or unexpected behavior, then you’re cutting corners if you don’t have tests, whether you use 3rd-party code or not.
[ original gist 12 July 2013 ]
Instead of trying to extract a private function, we can rely on mocking/spying. This gist post shows how to use the Function() constructor to replace an internal call so that we can mock, spy or stub.
Continue reading “Mocking – not testing – private functions in JavaScript”
[originally posted 2014-03-27]
Some time in 2013 as I was working through some JavaScript constructor inheritance tests, I found an example of static inheritance as an anti-pattern (meaning don’t bother with it) in the transpiled code from a CoffeeScript tutorial.
[originally posted 2014-03-24]
Here are two quick and dirty examples showing how to preserve /*** multiline string comments ***/ when using uglifyjs (i.e., uglify 2.0). The first uses the basic uglify cli approach, while the second example uses gulp.
Continue reading “Preserving multi-line comment-style strings with UglifyJS2”
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