# Measure exceptions

You can send exception events to measure the number and type of crashes or
errors that occur on a web page. This page describes how to use gtag.js to send
exceptions to Google Analytics.

## Implementation

When an error occurs, send an exception event to Google Analytics:

    gtag('event', 'exception', {<exception_parameters>});

where `<exception_parameters>` is one or more parameter-value pairs. Separate
each pair by a comma. For example, this command sends a nonfatal error
exception.

    gtag('event', 'exception', {
      'description': 'error_description',
      'fatal': false   // set to true if the error is fatal
    });

## Exception parameters

The following table lists the exception parameters:

| Parameter name | Data type | Required | Description |
|---|---|---|---|
| `description` | string | No | A description of the error. |
| `fatal` | boolean | No | `true` if the error was fatal. |

## Example

Given the following function:

    function divide(x, y) {
      if (y === 0) {
        throw "Division by zero";
      }
      return x/y;
    }

the following code will send an exception event to Google Analytics if the
divisor y is zero:

    var x = document.getElementById('x').value;
    var y = document.getElementById('y').value;

    try {
      var r = divide(x, y);
    } catch(err) {
      gtag('event', 'exception', {
        'description': err,
        'fatal': false
      });
    }