Turn JSON / POJO into Firestore Fields for REST API

get-fields.js

//only handles integerValue, doubleValue, stringValue and booleanValue
const getType = (val) => {
    if (val === null) return 'nullValue'
    const t = typeof val
    switch (t) {
        case 'number': return n % 1 === 0 ? 'integerValue' : 'doubleValue'
        case 'string':
        case 'boolean':
            return t + 'Value'
    }
}
//@param obj json/pojo
const getFields = (obj) => Object.keys(obj)
    .map((k) => ({ [k]: {[getType(obj[k])]: obj[k] }}))
    .reduce((acc, cv) => ({...acc, ...cv}), {})