Completion values in JavaScript
Written by Stefan Judis
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This post is part of my Today I learned series in which I share all my web development learnings.
Paul Irish tweeted a while back a code snippet that puzzled him (and me).
> "omg"; var x = 4;
// "omg"
> eval( `"omg"; var x = 4;` );
// "omg"
We both expected that the "return value" of this lines will be undefined. It turns out what we see after evaluating these lines in a JavaScript console are not return values but rather a statement completion values. If you want to dig deeper in this topic Matt Zeunert enlightened me with his article.
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About the author
Frontend nerd with over ten years of experience, "Today I Learned" blogger, conference speaker, Tiny helpers maintainer, and DevRel at Checkly.