Go's url.EncodeQuery in TypeScript

How to use

Install via yarn add locutus and import: import { EncodeQuery } from 'locutus/golang/url/EncodeQuery'.

Or with CommonJS: const { EncodeQuery } = require('locutus/golang/url/EncodeQuery')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	EncodeQuery('b=2&b=3&a=1')	'a=1&b=2&b=3'
2	EncodeQuery('z=last&a=first')	'a=first&z=last'
3	EncodeQuery('flag&empty=')	'empty=&flag='

Notes

• Encodes query values with deterministic key ordering, mirroring Go’s url.Values.Encode.

Dependencies

This function uses the following Locutus functions:

• ParseQuery (golang/url)
• QueryEscape (golang/url)

Here's what our current TypeScript equivalent to Go's url.EncodeQuery looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

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import { ParseQuery } from './ParseQuery.ts'
import { QueryEscape } from './QueryEscape.ts'

type QueryValue = string | string[]
type QueryValues = Record<string, QueryValue>

const normalizeValues = (input: QueryValues): Record<string, string[]> => {
  const out: Record<string, string[]> = {}

  for (const key of Object.keys(input)) {
    const raw = input[key]
    if (Array.isArray(raw)) {
      out[key] = raw.map((value) => String(value))
      continue
    }
    out[key] = [String(raw)]
  }

  return out
}

export function EncodeQuery(values: QueryValues | string): string {
  //      discuss at: https://locutus.io/golang/url/EncodeQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes query values with deterministic key ordering, mirroring Go's url.Values.Encode.
  //       example 1: EncodeQuery('b=2&b=3&a=1')
  //       returns 1: 'a=1&b=2&b=3'
  //       example 2: EncodeQuery('z=last&a=first')
  //       returns 2: 'a=first&z=last'
  //       example 3: EncodeQuery('flag&empty=')
  //       returns 3: 'empty=&flag='

  const parsed: Record<string, string[]> =
    typeof values === 'string' ? ParseQuery(values) : normalizeValues(values as QueryValues)

  const pairs: string[] = []
  const keys = Object.keys(parsed).sort()

  for (const key of keys) {
    const entries = parsed[key] ?? []
    if (entries.length === 0) {
      pairs.push(`${QueryEscape(key)}=`)
      continue
    }

    for (const value of entries) {
      pairs.push(`${QueryEscape(key)}=${QueryEscape(value)}`)
    }
  }

  return pairs.join('&')
}

import { ParseQuery } from './ParseQuery.ts'
import { QueryEscape } from './QueryEscape.ts'

const normalizeValues = (input) => {
  const out = {}

  for (const key of Object.keys(input)) {
    const raw = input[key]
    if (Array.isArray(raw)) {
      out[key] = raw.map((value) => String(value))
      continue
    }
    out[key] = [String(raw)]
  }

  return out
}

export function EncodeQuery(values) {
  //      discuss at: https://locutus.io/golang/url/EncodeQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes query values with deterministic key ordering, mirroring Go's url.Values.Encode.
  //       example 1: EncodeQuery('b=2&b=3&a=1')
  //       returns 1: 'a=1&b=2&b=3'
  //       example 2: EncodeQuery('z=last&a=first')
  //       returns 2: 'a=first&z=last'
  //       example 3: EncodeQuery('flag&empty=')
  //       returns 3: 'empty=&flag='

  const parsed = typeof values === 'string' ? ParseQuery(values) : normalizeValues(values)

  const pairs = []
  const keys = Object.keys(parsed).sort()

  for (const key of keys) {
    const entries = parsed[key] ?? []
    if (entries.length === 0) {
      pairs.push(`${QueryEscape(key)}=`)
      continue
    }

    for (const value of entries) {
      pairs.push(`${QueryEscape(key)}=${QueryEscape(value)}`)
    }
  }

  return pairs.join('&')
}

// golang/url/QueryUnescape (Locutus dependency module)
function QueryUnescape(s: string): string {
  //      discuss at: https://locutus.io/golang/url/QueryUnescape
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Decodes query-escaped strings where `+` maps to a space.
  //       example 1: QueryUnescape('a+b%2Bc')
  //       returns 1: 'a b+c'
  //       example 2: QueryUnescape('https%3A%2F%2Flocutus.io%2F%3Fq%3Dgo+lang')
  //       returns 2: 'https://locutus.io/?q=go lang'
  //       example 3: QueryUnescape('%2Bplus')
  //       returns 3: '+plus'

  const raw = String(s).replace(/\+/g, ' ')
  try {
    return decodeURIComponent(raw)
  } catch {
    throw new TypeError('QueryUnescape(): invalid query escape')
  }
}

// golang/url/ParseQuery (Locutus dependency module)
type QueryValues = Record<string, string[]>

function ParseQuery(query: string): QueryValues {
  //      discuss at: https://locutus.io/golang/url/ParseQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Parses URL-encoded key/value pairs into arrays per key.
  //       example 1: ParseQuery('a=1&b=2&b=3')
  //       returns 1: {a: ['1'], b: ['2', '3']}
  //       example 2: ParseQuery('q=go+lang&x=%2B')
  //       returns 2: {q: ['go lang'], x: ['+']}
  //       example 3: ParseQuery('empty=&flag')
  //       returns 3: {empty: [''], flag: ['']}

  const raw = String(query)
  if (raw === '') {
    return {}
  }

  const out: QueryValues = {}
  const pairs = raw.split('&')

  for (const pair of pairs) {
    if (pair === '') {
      continue
    }

    const separator = pair.indexOf('=')
    const keyRaw = separator >= 0 ? pair.slice(0, separator) : pair
    const valueRaw = separator >= 0 ? pair.slice(separator + 1) : ''
    const key = QueryUnescape(keyRaw)
    const value = QueryUnescape(valueRaw)

    const existing = out[key]
    if (existing) {
      existing.push(value)
    } else {
      out[key] = [value]
    }
  }

  return out
}

// golang/url/QueryEscape (Locutus dependency module)
const strictEncodeURIComponent = (value: string): string =>
  encodeURIComponent(value).replace(/[!'()*]/g, (char) => `%${char.charCodeAt(0).toString(16).toUpperCase()}`)

function QueryEscape(s: string): string {
  //      discuss at: https://locutus.io/golang/url/QueryEscape
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes a query component where spaces become '+'.
  //       example 1: QueryEscape('a b+c')
  //       returns 1: 'a+b%2Bc'
  //       example 2: QueryEscape('https://locutus.io/?q=go lang')
  //       returns 2: 'https%3A%2F%2Flocutus.io%2F%3Fq%3Dgo+lang'
  //       example 3: QueryEscape('100%')
  //       returns 3: '100%25'

  return strictEncodeURIComponent(String(s)).replace(/%20/g, '+')
}

// golang/url/EncodeQuery (target function module)
type QueryValue = string | string[]

type QueryValues = Record<string, QueryValue>

const normalizeValues = (input: QueryValues): Record<string, string[]> => {
  const out: Record<string, string[]> = {}

  for (const key of Object.keys(input)) {
    const raw = input[key]
    if (Array.isArray(raw)) {
      out[key] = raw.map((value) => String(value))
      continue
    }
    out[key] = [String(raw)]
  }

  return out
}

function EncodeQuery(values: QueryValues | string): string {
  //      discuss at: https://locutus.io/golang/url/EncodeQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes query values with deterministic key ordering, mirroring Go's url.Values.Encode.
  //       example 1: EncodeQuery('b=2&b=3&a=1')
  //       returns 1: 'a=1&b=2&b=3'
  //       example 2: EncodeQuery('z=last&a=first')
  //       returns 2: 'a=first&z=last'
  //       example 3: EncodeQuery('flag&empty=')
  //       returns 3: 'empty=&flag='

  const parsed: Record<string, string[]> =
    typeof values === 'string' ? ParseQuery(values) : normalizeValues(values as QueryValues)

  const pairs: string[] = []
  const keys = Object.keys(parsed).sort()

  for (const key of keys) {
    const entries = parsed[key] ?? []
    if (entries.length === 0) {
      pairs.push(`${QueryEscape(key)}=`)
      continue
    }

    for (const value of entries) {
      pairs.push(`${QueryEscape(key)}=${QueryEscape(value)}`)
    }
  }

  return pairs.join('&')
}

// golang/url/QueryUnescape (Locutus dependency module)
function QueryUnescape(s) {
  //      discuss at: https://locutus.io/golang/url/QueryUnescape
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Decodes query-escaped strings where `+` maps to a space.
  //       example 1: QueryUnescape('a+b%2Bc')
  //       returns 1: 'a b+c'
  //       example 2: QueryUnescape('https%3A%2F%2Flocutus.io%2F%3Fq%3Dgo+lang')
  //       returns 2: 'https://locutus.io/?q=go lang'
  //       example 3: QueryUnescape('%2Bplus')
  //       returns 3: '+plus'

  const raw = String(s).replace(/\+/g, ' ')
  try {
    return decodeURIComponent(raw)
  } catch {
    throw new TypeError('QueryUnescape(): invalid query escape')
  }
}

// golang/url/ParseQuery (Locutus dependency module)
function ParseQuery(query) {
  //      discuss at: https://locutus.io/golang/url/ParseQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Parses URL-encoded key/value pairs into arrays per key.
  //       example 1: ParseQuery('a=1&b=2&b=3')
  //       returns 1: {a: ['1'], b: ['2', '3']}
  //       example 2: ParseQuery('q=go+lang&x=%2B')
  //       returns 2: {q: ['go lang'], x: ['+']}
  //       example 3: ParseQuery('empty=&flag')
  //       returns 3: {empty: [''], flag: ['']}

  const raw = String(query)
  if (raw === '') {
    return {}
  }

  const out = {}
  const pairs = raw.split('&')

  for (const pair of pairs) {
    if (pair === '') {
      continue
    }

    const separator = pair.indexOf('=')
    const keyRaw = separator >= 0 ? pair.slice(0, separator) : pair
    const valueRaw = separator >= 0 ? pair.slice(separator + 1) : ''
    const key = QueryUnescape(keyRaw)
    const value = QueryUnescape(valueRaw)

    const existing = out[key]
    if (existing) {
      existing.push(value)
    } else {
      out[key] = [value]
    }
  }

  return out
}

// golang/url/QueryEscape (Locutus dependency module)
const strictEncodeURIComponent = (value) =>
  encodeURIComponent(value).replace(/[!'()*]/g, (char) => `%${char.charCodeAt(0).toString(16).toUpperCase()}`)

function QueryEscape(s) {
  //      discuss at: https://locutus.io/golang/url/QueryEscape
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes a query component where spaces become '+'.
  //       example 1: QueryEscape('a b+c')
  //       returns 1: 'a+b%2Bc'
  //       example 2: QueryEscape('https://locutus.io/?q=go lang')
  //       returns 2: 'https%3A%2F%2Flocutus.io%2F%3Fq%3Dgo+lang'
  //       example 3: QueryEscape('100%')
  //       returns 3: '100%25'

  return strictEncodeURIComponent(String(s)).replace(/%20/g, '+')
}

// golang/url/EncodeQuery (target function module)
const normalizeValues = (input) => {
  const out = {}

  for (const key of Object.keys(input)) {
    const raw = input[key]
    if (Array.isArray(raw)) {
      out[key] = raw.map((value) => String(value))
      continue
    }
    out[key] = [String(raw)]
  }

  return out
}

function EncodeQuery(values) {
  //      discuss at: https://locutus.io/golang/url/EncodeQuery
  // parity verified: Go 1.23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Encodes query values with deterministic key ordering, mirroring Go's url.Values.Encode.
  //       example 1: EncodeQuery('b=2&b=3&a=1')
  //       returns 1: 'a=1&b=2&b=3'
  //       example 2: EncodeQuery('z=last&a=first')
  //       returns 2: 'a=first&z=last'
  //       example 3: EncodeQuery('flag&empty=')
  //       returns 3: 'empty=&flag='

  const parsed = typeof values === 'string' ? ParseQuery(values) : normalizeValues(values)

  const pairs = []
  const keys = Object.keys(parsed).sort()

  for (const key of keys) {
    const entries = parsed[key] ?? []
    if (entries.length === 0) {
      pairs.push(`${QueryEscape(key)}=`)
      continue
    }

    for (const value of entries) {
      pairs.push(`${QueryEscape(key)}=${QueryEscape(value)}`)
    }
  }

  return pairs.join('&')
}

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Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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