JavaScriptException in execute_script method

Question

def send(self, message):
    try:
        textArea = self.driver.find_element_by_xpath("//textarea[@placeholder='Message...']")
        textArea.clear()
        self.driver.execute_script("arguments[0].value='" + message + "'", textArea) # Error right here
        textArea.send_keys(Keys.SPACE)
        sendButton = self.driver.find_element_by_xpath("//button[contains(text(), 'Send')]").click()

    except NoSuchElementException or StaleElementReferenceException as ex:
        print("Исключение в send()")
        print(ex)

Up to this point, the fifth line worked, but now I just can’t figure out what the problem is. And the variables have correct values.

File "D:\PROJECTS\BLD_Project\main.py", line 187, in send
    self.driver.execute_script("arguments[0].value='" + message + "'", textArea)
  File "D:\PROJECTS\INST\venv\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 878, in execute_script
    return self.execute(command, {
  File "D:\PROJECTS\INST\venv\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 424, in execute
    self.error_handler.check_response(response)
  File "D:\PROJECTS\INST\venv\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 247, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.JavascriptException: Message: javascript error: Unexpected identifier

Does `message` happen to contain quotes, newlines or other "special" characters? — Thomas, Jan 26 '22 at 13:01
@Thomas can you provide a list of special characters? It looks like you are right. — Дмитрий Гуща, Jan 26 '22 at 13:08

score 2 · Accepted Answer · answered Jan 27 '22 at 07:44

2

You seem to be running into escaping troubles. If message contains a quote character, for example O'Hara, you'd end up with a syntax error in the executed JavaScript code:

arguments[0].value='O'Hara'

The solution is to use the arguments array that you're already using, to pass the message string as well:

self.driver.execute_script("arguments[0].value = arguments[1]", textArea, message)

answered Jan 27 '22 at 07:44

Thomas

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it's difficult for me to understand this behavior, where exactly did I go wrong ? – cruisepandey Jan 27 '22 at 08:07
moreover, I run the code that I have given, with multiple combination of special characters and it did work on those occasions as well. – cruisepandey Jan 27 '22 at 08:13
Do you understand why `arguments[0].value='O'Hara'` is a problem? – Thomas Jan 27 '22 at 09:42

cruisepandey · Answer 2 · 2022-01-27T10:01:04.893

-1

Assuming message is a string, you can use setAttribute inside execute_script like below:

textArea = self.driver.find_element_by_xpath("//textarea[@placeholder='Message...']")
self.driver.execute_script(f"arguments[0].setAttribute('value', '{message}')", textArea)

to pass message variable into textArea web element.

Update:

edited Jan 27 '22 at 10:01

answered Jan 26 '22 at 13:05

cruisepandey

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It does not address the problem. If the original code gives a syntax error, so will this one. – Thomas Jan 27 '22 at 09:41
@Thomas: I don't see any syntax error, I made a sample.html file with an input tag and could update the input field with my selenium script having execute_script, whatever I have mentioned above. It did work and did not throw any syntax error. – cruisepandey Jan 27 '22 at 09:52
If you didn't see any syntax error, you were failing to reproduce OP's issue in the first place. Read the question again. What happened if you set `message = "O'Hara"` in your Python code? – Thomas Jan 27 '22 at 09:55
@Thomas: See by yourself, updated with screenshot. – cruisepandey Jan 27 '22 at 09:56
he had problem at this line `self.driver.execute_script("arguments[0].value='" + message + "'", textArea) # Error right here` and I could resolve this, I am not here to make you agree on this, but I don't see anyway you should downvote this answer. Cause this actually works. – cruisepandey Jan 27 '22 at 09:58
It works _exactly as well as the original code_. Not worse, but also not better. Which is: fine if `message` is `This is stackoverflow`, and broken if `message` is `O'Hara`. – Thomas Jan 27 '22 at 10:00
@Thomas: Again updated! with multiple special character combinations. – cruisepandey Jan 27 '22 at 10:01
The screenshot is meaningless; the syntax error is not in the Python code. `arguments[0].setAttribute('value', 'This is stack'ove'rfl'ow')` is now the JavaScript you're producing. Which will fail as soon as the browser tries to run it. (Here ends my will to discuss this further.) – Thomas Jan 27 '22 at 10:05
@Thomas: that's the point, it did work with my sample.html file but anyway, I can not spend my precious time on this. You are right ! – cruisepandey Jan 27 '22 at 10:06

JavaScriptException in execute_script method

2 Answers2