NodeJS async/await error propagation

async-await-error-handling.js

// direct as promise
;(function () {
  const prefix = '[direct-promise level]'
  async function direct () {
    throw new Error(`${prefix} explosion`)
  }

  direct().then(() => {
    console.log(`${prefix} success`)
  }).catch(err => {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  })
})()

// direct as async/await
;(async function () {
  const prefix = '[direct-async level]'
  async function direct () {
    throw new Error(`${prefix} explosion`)
  }

  try {
    const result = await direct()
    console.log(`${prefix} success with result=${result}`)
  } catch (err) {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  }
})()

// 1 level deep
;(async function () {
  const prefix = '[1 level]'
  async function level1 () {
    async function direct () {
      throw new Error(`${prefix} explosion`)
    }
    await direct()
  }

  try {
    const result = await level1()
    console.log(`${prefix} success with result=${result}`)
  } catch (err) {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  }
})()

// 2 levels deep
;(async function () {
  const prefix = '[2 level]'
  async function level2 () {
    async function level1 () {
      async function direct () {
        throw new Error(`${prefix} explosion`)
      }
      await direct()
    }
    await level1()
  }

  try {
    const result = await level2()
    console.log(`${prefix} success with result=${result}`)
  } catch (err) {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  }
})()

// 3 levels deep
;(async function () {
  const prefix = '[3 level]'
  async function level3 () {
    async function level2 () {
      async function level1 () {
        async function direct () {
          throw new Error(`${prefix} explosion`)
        }
        await direct()
      }
      await level1()
    }
    await level2()
  }

  try {
    const result = await level3()
    console.log(`${prefix} success with result=${result}`)
  } catch (err) {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  }
})()

// inside a .then()
;(async function () {
  const prefix = '[in .then()]'
  function level2 () {
    async function level1 () {
      async function direct () {
        throw new Error(`${prefix} explosion`)
      }
      await direct()
    }
    return level1()
  }

  Promise.resolve().then(async () => {
    return level2()
  }).then(result => {
    console.log(`${prefix} success with result=${result}`)
  }).catch(err => {
    console.error(`${prefix} failed with error=${err}`) // we hit this case
  })
})()

// inside a callback with try-catch
;(async function () {
  const prefix = '[in cb() try-catch]'
  async function direct () {
    throw new Error(`${prefix} explosion`)
  }

  function doCallback (cb) {
    cb()
  }

  doCallback(async () => {
    try {
      await direct()
      console.log(`${prefix} success`)
    } catch (err) {
      console.error(`${prefix} failed with error=${err}`) // we hit this case
    }
  })
})()

// inside a callback with .catch()
;(async function () {
  const prefix = '[in cb() .catch()]'
  async function direct () {
    throw new Error(`${prefix} explosion`)
  }

  function doCallback (cb) {
    cb()
  }

  doCallback(async () => {
    await direct().catch(err => {
      console.error(`${prefix} failed with error=${err}`) // we hit this case
    })
    console.log(`${prefix} will run after .direct() has returned`)
  })
})()