prune.js

// https://gist.github.com/jniac/39eabea6b06a9be5be348c11447c249c
/**
 * 'prune' will simplify any tree (target) by removing any 'autoKey'
 * found by its inner value. eg:
 * 
 * `prune({ text:{ en:'foo', fr:'toto' }}, 'en') // -> { text:'foo' }`  
 * `prune({ text:{ en:'foo', fr:'toto' }}, 'fr') // -> { text:'toto' }`
 * @param {object} target 
 * @param  {...string} autoKeys 
 */
function prune(target, ...autoKeys) {

    if (target && typeof target === 'object') {

        for (const autoKey of autoKeys) {

            if (autoKey in target) {

                return prune(target[autoKey], ...autoKeys)
            }
        }

        const clone = Array.isArray(target) ? [] : {}

        for (const [key, value] of Object.entries(target)) {

            if (value && typeof value === 'object') {

                clone[key] = prune(value, ...autoKeys)

            } else {

                clone[key] = value
            }
        }

        return clone
    }

    return target
}

export { prune }
export default prune

usage

someData = {
    name: {
        __DEV__:'foo',
        __PROD__:'Foo!',
    },
    info: {
        __DEV__: { message:'app is in development', aspect:'TBD' },
        __PROD__: { message:'that app is cool', aspect: { __MOBILE__:'9/16', __TABLET__:'4/3', __DESKTOP__:'16/9' } },
    },
}

prune(someData, '__PROD__', '__TABLET__')

output:

{
    name: "Foo!",
    info: {  message:"that app is cool", aspect:"4/3" },
}