encodeForm.ts

import { is } from 'is'
import { Lookup } from 'types'

// Reuse one array for all encoding.
const pairs: string[] = []

export function encodeForm(values: Lookup) {
  for (const key in values) {
    encodePair(key, values[key])
  }

  const str = pairs.join('&')
  pairs.length = 0
  return str
}

function encodePair(key: string, value: any) {
  if (is.defined(value)) {
    if (is.object(value)) {
      encodeObject(value, key)
    } else if (is.array(value)) {
      encodeArray(value, key)
    } else {
      pairs.push(encodeURIComponent(key) + '=' + encodeURIComponent(value))
    }
  }
}

function encodeObject(values: Lookup, parent: string) {
  for (const key in values) {
    encodePair(parent + '[' + key + ']', values[key])
  }
}

function encodeArray(values: readonly any[], parent: string) {
  for (let i = 0; i < values.length; i++) {
    encodePair(parent + '[' + i + ']', values[i])
  }
}