@multipart/append-field/src/lib/set-value.js

[fork] W3C HTML JSON form compliant field appender Written In ES6 And Optimised With JavaScript Compiler.

function valueType (value) {
  if (value === undefined) return 'undefined'
  if (Array.isArray(value)) return 'array'
  if (typeof value == 'object') return 'object'
  return 'scalar'
}

function setLastValue(context, step, currentValue, entryValue) {
  switch (valueType(currentValue)) {
  case 'undefined':
    if (step.append) {
      context[step.key] = [entryValue]
    } else {
      context[step.key] = entryValue
    }
    break
  case 'array':
    context[step.key].push(entryValue)
    break
  case 'object':
    return setLastValue(currentValue, { type: 'object', key: '', last: true }, currentValue[''], entryValue)
  case 'scalar':
    context[step.key] = [context[step.key], entryValue]
    break
  }

  return context
}

export default function setValue(context, step, currentValue, entryValue) {
  if (step.last) return setLastValue(context, step, currentValue, entryValue)

  let obj
  switch (valueType(currentValue)) {
  case 'undefined':
    if (step.nextType == 'array') {
      context[step.key] = []
    } else {
      context[step.key] = {}
    }
    return context[step.key]
  case 'object':
    return context[step.key]
  case 'array':
    if (step.nextType == 'array') {
      return currentValue
    }

    obj = {}
    context[step.key] = obj
    currentValue.forEach(function (item, i) {
      if (item !== undefined) obj['' + i] = item
    })

    return obj
  case 'scalar':
    obj = {}
    obj[''] = currentValue
    context[step.key] = obj
    return obj
  }
}