mirror of
https://github.com/jbranchaud/til
synced 2026-01-03 15:18:01 +00:00
29 lines
999 B
Markdown
29 lines
999 B
Markdown
# Matching A Computed Property In Function Args
|
|
|
|
The [computed property name](http://es6-features.org/#ComputedPropertyNames)
|
|
feature of ES6 allows you to reference a variable in object assignments and
|
|
destructurings. This syntax is flexible enough that it can be used in the
|
|
arguments portion of a function declaration. In fact, it can even be matched
|
|
against another argument -- allowing the creation of some handy, yet terse
|
|
functions.
|
|
|
|
```javascript
|
|
const get = (key, { [key]: foundValue }) => foundValue;
|
|
```
|
|
|
|
Notice that the first argument, `key`, will match against the computed
|
|
property name in the second argument. The `foundValue` will correspond to
|
|
whatever `key` maps to in the given object.
|
|
|
|
This `get` function can then be used like so.
|
|
|
|
```javascript
|
|
const stuff = { a: 1, b: 2, c: 3 };
|
|
|
|
console.log("Get a:", get("a", stuff)); // Get a: 1
|
|
console.log("Get d:", get("d", stuff)); // Get d: undefined
|
|
```
|
|
|
|
h/t
|
|
[@sharifsbeat](https://twitter.com/sharifsbeat/status/1084235020183748610)
|