toJson.js

const treeArray = [
    { path: 'name', value: 'name' },
    { path: 'meta.age', value: 'age' },
    { path: 'meta.eyes', value: 'eyes' },
    { path: 'friends.[0]', value: 'friends 0' },
    { path: 'friends.[1]', value: 'friends 1' },
    { path: 'friends.[2]', value: 'friends 2' },
    { path: 'friends.[3].name', value: 'friends 3 name' },
]

const makeJson = (arrayOfNodes) => { /* ... */ }

console.log(makeJson(treeArray))

/* 
{ 
    name: 'name',
    meta: { 
        age: 'age', 
        eyes: 'eyes' 
    },
    friends: [ 
        'friends 0',
        'friends 1',
        'friends 2',
        { 
            name: 'friends 3 name' 
        } 
    ] 
}
/*

Is this cheating?

import set from 'lodash/set'
const makeJson = (arrayOfNodes) => {
    const fixPath = (path) => path.replace('.[', '[')
    const json = {}
    arrayOfNodes.each(({path, value}) => {
        set(json, fixPath(path), value)
    })
    return json
}