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lastError
, you are expected to check for the error when you handle the result of the function. If lastError
has been set and you don't check it within the callback function, then an error will be raised.Syntax
var myError = chrome.runtime.lastError; // null or Error object
This API is also available as browser.runtime.lastError
.
Value
An Error object representing the error. The message
property is a string
with a human-readable description of the error . If lastError
has not been set, the value is null
.
Examples
There are two different ways add-ons can call asynchronous functions:
- By passing in a callback to the function, which is called with the function's result.
- By omitting the callback and using the
browser
namespace, in which case the function will return aPromise
.
In the first case, if the function can set lastError
you should check it in the callback. For example:
function logCookie(c) {
if (chrome.runtime.lastError) {
console.error(chrome.runtime.lastError);
} else {
console.log(c);
}
}
chrome.cookies.set(
{url: "https://developer.mozilla.org/"},
logCookie
);
In the second case, lastError
will be passed into the second argument of Promise.then()
:
function logCookie(c) {
console.log(c);
}
function logError(e) {
console.error(e);
}
var setCookie = browser.cookies.set(
{url: "https://developer.mozilla.org/"}
);
setCookie.then(logCookie, logError);
Note: runtime.lastError
is an alias for extension.lastError
: they are set together, and checking either one will work.
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Chrome | Edge | Firefox | Firefox for Android | Opera | |
---|---|---|---|---|---|
Basic support | Yes | Yes | 47.0 | 48.0 | 33 |
Compatibility notes
Chrome
- lastError is not an Error object. Instead, it is a plain Object with the error text as the string value of the 'message' property.
Opera
- lastError is not an Error object. Instead, it is a plain Object with the error text as the string value of the 'message' property.
Example add-ons
This API is based on Chromium's chrome.runtime
API. This documentation is derived from runtime.json
in the Chromium code.
Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.
// Copyright 2015 The Chromium Authors. All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.