rep-rev

Replace / revive for the built-in JSON object.

You were ever doing this const str = JSON.stringify(obj, null, 2) and thinking about the null you are passing here?

What if you pass something else?

That's where rep-rev comes into play.

The two methods of JSON each take an additional parmeter:

JSON.stringify(value, replacer, space);
JSON.parse(text, reviver);

replacer and reviver.

rep-rev utilizes those to provide a way of manipulating the values going in and out of JSON.stringify() resp. JSON.parse().

For example a Date: It stringifies just fine to a string, but stays a string when getting parsed. So you end up doing things like:

const items = JSON.parse(text);
for (const item of items) {
  item.date = new Date(item.date);
}

Time to

Get Started

Install

$ npm install rep-rev
# Or:
$ yarn add rep-rev

Simple Example

import {
  createRepRevCollection,
} from 'rep-rev';

const transformer = createRepRevCollection();
const items = JSON.parse(text, transformer.revive);

That's it. The default transformer collection has built-in rep-revs for Map, Set and Date.

All of these are transformed through an InstanceRepRev which creates / parses an intermediate format for the resulting JSON. E.g. a replaced()d Date becomes:

{
  "$class": "Date",
  "data": "2023-10-23T15:44:04.986Z"
}

A Map becomes:

{
  "$class": "Map",
  "data": [
    ["<key1>", "<value1>"],
    ["<key2>", "<value2>"]
  ]
}

The data-member can easily be serialized back into a Map or Date via new(data).

More Examples

There are two examples in the examples folder, I think, you get the gist of it. Planning on adding more.

That's all for now.

Oh, one more thing:

Q&A

• Can I transform json to json?
  Well... there is an experimental function transformJson(value, repl) that mimics the behaviour of JSON[stringify|parse] (I hope - unit tests still missing). You can use that with both a replace() or a revive() to map json to json.