What could be causing the SyntaxError with JavascriptExecutor: Unexpected identifier?

Question

What could be causing the SyntaxError with JavascriptExecutor: Unexpected identifier?

Python

PythonExecutor py = (PythonExecutor) driver;
Boolean ready = (Boolean)py.executeScript("the following Python code");

Python Code

var ready = False;
window.onload = def check_ready():
    ready = True

def sleep():
    return new Promise(resolve => setTimeout(resolve, 2000))

for i in range(30):
    if ready:
        return True
    await sleep()
    
return False;

UPDATE: Apologies for the syntax error "funtion" in my previous post. It was a typo and not part of my actual code. Despite fixing all syntax errors, I still encounter "SyntaxError: Unexpected identifier".

The purpose of this code is to wait for a specified period for the page to finish loading. While I normally use document.readyState to determine this, there are instances where Chrome stops loading abruptly and document.readyState remains stuck for over 5 minutes. To counter this issue, I am experimenting with creating single-threaded code that simulates a multi-threaded process.

Given JavaScript's single-threaded nature (a limitation for such a versatile language), we must think outside the box.

This code functions properly in the browser console when replacing return true; with console.log('true'); and return false; with console.log('false');, so the problem doesn't seem apparent.

javascript java selenium browser-automation javascript-injection

Answer 1

Answer №1

It appears that your JavaScript code contains some errors.

The first error can be found in the third line where you have written

window.sleep = funtion() { return new Promise(resolve => setTimeout(resolve, 2000)); }

, there seems to be a typo in the spelling of function.

The second mistake is using await without declaring async in your function definition. Remember, async is necessary to ensure that the function returns a promise, while await should only be used inside async functions.

The third issue arises when you try to return true; from within the for loop of an if condition, which is invalid because it is not enclosed within a function.

Another problem is that you are not invoking the window.onload function, resulting in a false return even after the page has loaded.

Furthermore, the usage of incomplete resolve in the window.sleep function raises uncertainty about its functionality.

Lastly, returning false at the end of the code without any context renders it meaningless.

I have made modifications to the code to address these issues effectively, feel free to review it below:

var status = false;
window.sleep = function() { 
    return setTimeout(() => {
        console.log("=> Waited for 2 seconds...");
    }, 2000);
}
var getStatus = function() {
    for(var i = 0; i < 30; i++) {
        if(window.onload = function() {
            return true;
            }) {
            status = true;
            console.log(i+"). Loaded ? "+status);
            break;
        } else {
            console.log(i+"). Loaded ? "+status);
            sleep();
        }
    }
    return status;
}
getStatus();

Feel free to test the following Java code snippet that prints true upon page loading :

System.setProperty("webdriver.chrome.driver", "C:\\NotBackedUp\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
driver.get("http://www.google.com");
JavascriptExecutor js = (JavascriptExecutor) driver;
Boolean result = (Boolean) js.executeScript("var status = false;\r\n" + 
        "window.sleep = function() { \r\n" + 
        "   return setTimeout(() => {\r\n" + 
        "       console.log(\"=> Waited for 2 seconds...\");\r\n" + 
        "   }, 2000);\r\n" + 
        "}\r\n" + 
        "var getStatus = function() {\r\n" + 
        "   for(var i = 0; i < 30; i++) {\r\n" + 
        "       if(window.onload = function() {\r\n" + 
        "           return true;\r\n" + 
        "           }) {\r\n" + 
        "           status = true;\r\n" + 
        "           console.log(i+\"). Loaded ? \"+status);\r\n" + 
        "           break;\r\n" + 
        "       } else {\r\n" + 
        "           console.log(i+\"). Loaded ? \"+status);\r\n" + 
        "           sleep();\r\n" + 
        "       }\r\n" + 
        "   }\r\n" + 
        "   return status;\r\n" + 
        "}\r\n" + 
        "return getStatus();");
System.out.println(result);

I hope this modified version solves the previous issues...

Answer 2

It appears that your JavaScript code contains some errors.

The first error can be found in the third line where you have written

window.sleep = funtion() { return new Promise(resolve => setTimeout(resolve, 2000)); }

, there seems to be a typo in the spelling of function.

The second mistake is using await without declaring async in your function definition. Remember, async is necessary to ensure that the function returns a promise, while await should only be used inside async functions.

The third issue arises when you try to return true; from within the for loop of an if condition, which is invalid because it is not enclosed within a function.

Another problem is that you are not invoking the window.onload function, resulting in a false return even after the page has loaded.

Furthermore, the usage of incomplete resolve in the window.sleep function raises uncertainty about its functionality.

Lastly, returning false at the end of the code without any context renders it meaningless.

I have made modifications to the code to address these issues effectively, feel free to review it below:

var status = false;
window.sleep = function() { 
    return setTimeout(() => {
        console.log("=> Waited for 2 seconds...");
    }, 2000);
}
var getStatus = function() {
    for(var i = 0; i < 30; i++) {
        if(window.onload = function() {
            return true;
            }) {
            status = true;
            console.log(i+"). Loaded ? "+status);
            break;
        } else {
            console.log(i+"). Loaded ? "+status);
            sleep();
        }
    }
    return status;
}
getStatus();

Feel free to test the following Java code snippet that prints true upon page loading :

System.setProperty("webdriver.chrome.driver", "C:\\NotBackedUp\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
driver.get("http://www.google.com");
JavascriptExecutor js = (JavascriptExecutor) driver;
Boolean result = (Boolean) js.executeScript("var status = false;\r\n" + 
        "window.sleep = function() { \r\n" + 
        "   return setTimeout(() => {\r\n" + 
        "       console.log(\"=> Waited for 2 seconds...\");\r\n" + 
        "   }, 2000);\r\n" + 
        "}\r\n" + 
        "var getStatus = function() {\r\n" + 
        "   for(var i = 0; i < 30; i++) {\r\n" + 
        "       if(window.onload = function() {\r\n" + 
        "           return true;\r\n" + 
        "           }) {\r\n" + 
        "           status = true;\r\n" + 
        "           console.log(i+\"). Loaded ? \"+status);\r\n" + 
        "           break;\r\n" + 
        "       } else {\r\n" + 
        "           console.log(i+\"). Loaded ? \"+status);\r\n" + 
        "           sleep();\r\n" + 
        "       }\r\n" + 
        "   }\r\n" + 
        "   return status;\r\n" + 
        "}\r\n" + 
        "return getStatus();");
System.out.println(result);

I hope this modified version solves the previous issues...

What could be causing the SyntaxError with JavascriptExecutor: Unexpected identifier?

Answer №1

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