https://github.com/multiprocessio/preview
A large-object previewer for JavaScript
https://github.com/multiprocessio/preview
Last synced: 5 months ago
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A large-object previewer for JavaScript
- Host: GitHub
- URL: https://github.com/multiprocessio/preview
- Owner: multiprocessio
- License: other
- Created: 2021-07-27T16:27:05.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-01-02T20:50:54.000Z (over 3 years ago)
- Last Synced: 2023-03-03T23:04:33.718Z (about 2 years ago)
- Language: TypeScript
- Size: 160 KB
- Stars: 13
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# Preview
This library helps showing snippets of large or small objects. It is
particularly useful when trying to render snippets of very large
objects.
## Install
```bash
$ yarn add @multiprocess/preview
```
## Examples
While this library is a huge improvement on naive implementations like
`JSON.stringify(x).slice(0, 1000)` for large objects (say 70,000
elements), it's easier to show a small object in an example. So we'll
display a small object but overwrite `preview`'s default number of
results to show.
```javascript
import { preview } from '@multiprocess/preview';
// The default is 20, so we make it smaller.
const startingNumber = 2;
console.log(preview([
{ a: 1, b: 3, c: 5 },
{ a: 12, b: 8, c: 5 },
{ a: 13, b: 3, c: 9 },
], startingNumber));
```
Once it reaches the starting number of keys, it stops printing
elements. As it recurses into inner objects, the number of keys
shrinks each time as well.
Here is the output of the above script:
```json
[
{ "a": 1, ... },
{ "a": 12, ... },
...
]
```
Ellipsis are literally printed. They are only printed if elements have
been skipped by the preview.
### Another example
Here is another example of a more complex object:
```
import { preview } from 'preview';
const startingNumber = 4;
console.log(preview(
{ a: 12, b: [1, 3, 4], c: null, d: { n: 'foo', m: 19, l: [12] } },
startingNumber,
))
```
And the result:
```json
{
"a": 12,
"b": [ 1, 3, ... ],
"c": null,
"d": { "l": [ 12 ], "m": 19, ... }
}
```
Here, ellipsis only show up in the inner objects and not the outer
object because no keys in the outer object were skipped. There were
only four keys and the starting number of keys was four.
## Internals
For more details, check out this [blog
post](https://datastation.multiprocess.io/blog/2021-07-15-writing-an-efficient-javascript-object-previewer.html).
## Users
* [DataStation](https://github.com/multiprocessio/datastation)
## License
Apache-2.0, see [./LICENSE.md](./LICENSE.md).