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
browsernamespace, 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 {{WebExtAPIRef("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.
{{WebExtBrowserCompat}}
{{WebExtExamples}}
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.
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