PHP's function_exists in TypeScript

How to use

Install via yarn add locutus and import: import { function_exists } from 'locutus/php/funchand/function_exists'.

Or with CommonJS: const { function_exists } = require('locutus/php/funchand/function_exists')

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	function_exists('isFinite')	true

Dependencies

This function uses the following Locutus functions:

• _phpRuntimeState (php/_helpers)

Here's what our current TypeScript equivalent to PHP's function_exists looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

Copy code

import { getPhpGlobalCallable } from '../_helpers/_phpRuntimeState.ts'

export function function_exists(funcName: string): boolean {
  //  discuss at: https://locutus.io/php/function_exists/
  // original by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Steve Clay
  // improved by: Legaev Andrey
  // improved by: Brett Zamir (https://brett-zamir.me)
  //   example 1: function_exists('isFinite')
  //   returns 1: true

  return typeof getPhpGlobalCallable(funcName) === 'function'
}

import { getPhpGlobalCallable } from '../_helpers/_phpRuntimeState.ts'

export function function_exists(funcName) {
  //  discuss at: https://locutus.io/php/function_exists/
  // original by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Steve Clay
  // improved by: Legaev Andrey
  // improved by: Brett Zamir (https://brett-zamir.me)
  //   example 1: function_exists('isFinite')
  //   returns 1: true

  return typeof getPhpGlobalCallable(funcName) === 'function'
}

// php/_helpers/_phpTypes (Locutus helper dependency)
type PhpNullish = null | undefined

type PhpInput = {} | PhpNullish

type PhpAssoc<T = PhpInput> = { [key: string]: T }

type PhpCallableArgs = PhpInput[]

type PhpCallable<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput> = (
  ...args: TArgs
) => TResult

function isPhpCallable<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput>(
  value: PhpInput,
): value is PhpCallable<TArgs, TResult> {
  return typeof value === 'function'
}

// php/_helpers/_phpRuntimeState (Locutus helper dependency)
interface LocutusRuntimeContainer {
  php?: PhpAssoc<PhpInput>
}

interface PhpGlobalProcessLike {
  env?: PhpAssoc<string | undefined>
}

interface PhpGlobalBufferLike {
  from?: (...args: PhpInput[]) => PhpInput
}

interface PhpGlobalKnownEntryMap {
  process: PhpGlobalProcessLike
  Buffer: PhpGlobalBufferLike
}

type GlobalWithLocutus = {
  $locutus?: LocutusRuntimeContainer
  [key: string]: PhpInput
}

const globalContext: GlobalWithLocutus =
  typeof window === 'object' && window !== null ? window : typeof global === 'object' && global !== null ? global : {}

function getPhpGlobalEntry<TKey extends keyof PhpGlobalKnownEntryMap>(
  key: TKey,
): PhpGlobalKnownEntryMap[TKey] | undefined

function getPhpGlobalEntry(key: string): PhpInput | undefined

function getPhpGlobalEntry(key: string): PhpInput | undefined {
  const value = globalContext[key]
  return typeof value === 'undefined' ? undefined : value
}

function getPhpGlobalCallable<TArgs extends PhpInput[] = PhpInput[], TResult = PhpInput>(
  key: string,
): PhpCallable<TArgs, TResult> | undefined {
  const value = getPhpGlobalEntry(key)
  return isPhpCallable<TArgs, TResult>(value) ? value : undefined
}

// php/funchand/function_exists (target function module)
function function_exists(funcName: string): boolean {
  //  discuss at: https://locutus.io/php/function_exists/
  // original by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Steve Clay
  // improved by: Legaev Andrey
  // improved by: Brett Zamir (https://brett-zamir.me)
  //   example 1: function_exists('isFinite')
  //   returns 1: true

  return typeof getPhpGlobalCallable(funcName) === 'function'
}

// php/_helpers/_phpTypes (Locutus helper dependency)
function isPhpCallable(value) {
  return typeof value === 'function'
}

// php/_helpers/_phpRuntimeState (Locutus helper dependency)
const globalContext =
  typeof window === 'object' && window !== null ? window : typeof global === 'object' && global !== null ? global : {}

function getPhpGlobalEntry(key) {
  const value = globalContext[key]
  return typeof value === 'undefined' ? undefined : value
}

function getPhpGlobalCallable(key) {
  const value = getPhpGlobalEntry(key)
  return isPhpCallable(value) ? value : undefined
}

// php/funchand/function_exists (target function module)
function function_exists(funcName) {
  //  discuss at: https://locutus.io/php/function_exists/
  // original by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Steve Clay
  // improved by: Legaev Andrey
  // improved by: Brett Zamir (https://brett-zamir.me)
  //   example 1: function_exists('isFinite')
  //   returns 1: true

  return typeof getPhpGlobalCallable(funcName) === 'function'
}

Improve this function

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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