recurpolate

> Recursive interpolation of objects.


A portmanteau of "recurse" and "interpolate".

Useful e.g. to DRY up configurations, à la Spring.

Supports self-reference.
Supports array references (e.g. a.b[3].c).
Should detect circular references and throw error.

Install

 

Use

``js
import recurpolate from 'recurpolate'

const obj = {
api: {
base: 'https://api.example.com',
v0: '${api.base}/v0',
v1: '${api.base}/v1',
last: '${api.v1}'
},
services: {
profile: '${api.last}/profile',
fullProfile: '${services.profile}?view=full',
login: '${api.last}/login'
}
}

const resolved = recurpolate(obj)

console.log(resolved)
`
yields:
`js
{
base: {
api: {
base: 'https://api.example.com',
v0: 'https://api.example.com/v0',
v1: 'https://api.example.com/v1',
last: 'https://api.example.com/v1'
},
},
services: {
profile: 'https://api.example.com/v1/profile',
fullProfile: 'https://api.example.com/v1/profile?view=full',
login: 'https://api.example.com/v1/login'
}
}
`

Using the context option (or something like lodash.merge), you can easily created environment-specific configurations that all inherit from a default, e.g.:

`js
// default.json
{
"api": {
"products": "${api.base}/products/v1",
"coupons": "${api.base}/coupons/v2",
}
}
`

`js
// development.json
{
"api": {
"base": "https://dev.api.example.com"
}
}
`

`js
// production.json
{
"api": {
"base": "https://api.example.com"
}
}
`

`js
import recurpolate from 'recurpolate'
import defaultConfig from './default.json'
import developmentContext from './development.json'
import productionContext from './production.json'

const isProduction = process.env.NODE_ENV === 'production'
const context = isProduction ? productionContext : developmentContext

const config = recurpolate(defaultConfig, {
context
})
`

results in config being this in production:

`js
{
"api": {
"products": "https://api.example.com/products/v1",
"coupons": "https://api.example.com/coupons/v2",
}
}
`

but this in development:

`js
{
"api": {
"products": "https://dev.api.example.com/products/v1",
"coupons": "https://dev.api.example.com/coupons/v2",
}
}
`

$3

`js
const options = { / ... / }
recurpolate(obj, options)
`
#### context
> {Object} [=null]

If provided, serves as a fallback source for references when unresolved in object itself.
Allows interpolating to values that aren't actually in the source/target object.

#### maxDepth
> {Number} [=null]

Used to prevent long processing times or
infinite loops due to circular references missed by the library.

#### reportUnresolved
> {String} [='warn']

Reporting behavior when encountering a reference that resolves to an undefined value.

* 'warn', 'error', etc. - any method on console
* 'throw' - throws an error when
* 'quiet' - no warnings

#### replaceUnresolved
> {String} [='empty']

Replacement behavior when encountering a reference that resolves to an undefined value.

* 'empty' - removes the references from the strings, replacing with empty string
* 'keep' - keeps the references in the strings, e.g. ${some.undefined.value}`