API References

createTwoslasher

Twoslash runs a TypeScript language server to get the information, which could be a heavy operation to load and parse all the files it needs. In repetitive usages, you may not want to initialize the language server every simple time. Twoslash provides a createTwoslasher factory function allows you to cache the language servers and reuse the already initialized files.

import { createTwoslasher } from 'twoslash'

const twoslasher = createTwoslasher({
  // ...your custom options.
})

const result1 = twoslasher('import { ref } from "vue"', 'ts')
// The second time will be much faster as the types from `vue` is already.
const result2 = twoslasher('import { computed } from "vue"', 'ts')

This would result in a 5-20 times faster performance in repetitive usage.

To avoid getting interference across runs, it will reuse the language server with the same compilerOptions. Internally it holds a map of hashed compilerOptions to the language server instances.

You can retrieve the cached map and clear it when necessary, to avoid memory leaks:

import { createTwoslasher } from 'twoslash'

const twoslasher = createTwoslasher()

// Do something...

// Clear the cached language servers, free the memory.
twoslasher.getCacheMap()?.clear()

twoslasher

The twoslasher function is a shorthand for directly getting the result from the code. It will create a new TypeScript language server every time it is called. Ideally, createTwoslasher should be preferred.

import { twoslasher } from 'twoslash'

const code = `console.log("Hello World")`
const result = twoslasher(code, 'ts', { /* options */ })

twoslasherLegacy

The twoslasherLegacy function is provided to make the migration from @typescript/twoslash easier by converting the new result to the legacy format, learn more at Compatibility Layer sections.