JavaScript error

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The JavaScript error is a WebDriver error that occurs when a script the supplied by the user fails to execute.

The underlying cause of the execution error is often supplied in the error message, along with a stacktrace provided by the JavaScript engine in the browser.


Consider the following injected script which tries to use an undefined variable. In JavaScript this normally causes a ReferenceError to be thrown. WebDriver catches this error and serializes it as a JavaScript error:

from selenium import webdriver
from selenium.common import exceptions

session = webdriver.Firefox()
    session.execute_script("return foo")
except exceptions.JavaScriptException as e:


JavaScriptException: ReferenceError: foo is not defined

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 Contributors to this page: ato
 Last updated by: ato,