basic-usage.js

try {
  // your code is here
} catch(e) {
  // in case of exception, handle it here 
}

try-catch-async.js

try {
  await authenticate({});
} catch(e) {
  console.error('Unexpected error:', e.message)
}

try-catch-custom-exception.js

class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = this.constructor.name;
  }
}

function authenticate(request) {
  try {
    const { token } = request.query ?? {};

    if (!token) {
      throw new ValidationError ('Have not received [token]');
    }

  } catch(e) {
    console.log('Failed to authenticate', e.name, e.message)
  }
}

authenticate({});

try-catch-custom-exception1.js

class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = this.constructor.name;
  }
}


function authenticate(request) {
  try {
    const { token } = request.query ?? {};

    if (!token) {
      throw new ValidationError('have not received [token]');
    }

  } catch(e) {
    if (e instanceof ValidationError) {
      console.log('Could not pass gatekeeper:', e.message)
    } else {
      console.log('Failed to authenticate', e.name, e.message)
    }
  }
}

authenticate({});

try-catch-error.js

try {

  throw new Error('The most unexpected error in the world!');
  
} catch(e) {
  console.log(e.name); // Error Type: in this case just Error
  console.log(e.message); // Error Message: The string we’ve passed as an argument to the error constructor in the try block
  console.log(e.stack); // Error Stack: The calls sequence that led to the exception
}

try-catch-example.js

try {
  const { token } = request.query;

  if (!token) {
    throw new Error('Have not received [token]');
  }
  
} catch(e) {
  console.log('Failed to authenticate', e.messsage)
}

try-catch-finally.js

try {
  // your code is here
} catch(e) {
  // in case of exception, handle it here
} finally {
  // regardless of the result, this block is executed
}

try-catch-rethrow.js

class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = this.constructor.name;
  }
}

function authenticate(request) {
  try {
    const { token } = request.query ?? {};

    if (!token) {
      throw new ValidationError('have not received [token]');
    }

  } catch(e) {
    if (e instanceof ValidationError) {
      console.log('Could not pass gatekeeper:', e.message)
    } else {
      throw error; // retrow the error futher
    }
  }
}

authenticate({});

try-catch-rethrow1.js

class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = this.constructor.name;
  }
}

function validateRequest(request) {
  if (!token) {
    throw new ValidationError('have not received [token]');
  }
}

function authenticate(request) {
  try {
    validateRequest(request);
    
    // further processing...
    
  } catch(e) {
    if (e instanceof ValidationError) {
      console.log('Could not pass gatekeeper:', e.message)
    } else {
      throw error;
    }
  }
}

try {
  authenticate({});
} catch(e) {
  console.error('Unexpected error:', e.message)
}