Java Selenium Javascript executor fails to return desired result

Question

Java Selenium Javascript executor fails to return desired result

Attempting to execute a javascript function I created to gather all comments from an HTML site using xpath (requirement).
The function, when pasted directly into a browser without the 'return' statement, works flawlessly.
However, when run through the selenium 'javascriptexecutor', it returns an empty array.
I understand that javascript statements need to be enclosed in a " code "+ format, but for clarity purposes, I structured my code like this.
Hoping someone can assist me with this issue :)

ChromeDriver driver = new ChromeDriver();
String url = "AprivateSamplePage";
driver.get(url);
JavascriptExecutor js = (JavascriptExecutor) driver;
String text = (String)  js.executeScript("return nodes =[]; 
xPathResult=document.evaluate('//comment()',document,null,XPathResult.ANY_TYPE, null); 
nodes =[]; 
node = xPathResult.iterateNext(); 
while (node) {nodes.push(node.textContent); 
node =  xPathResult.iterateNext();}
nodes;").toString();
System.out.print(text);

The Output appears as follows:

Only local connections are allowed.
Okt 30, 2018 8:56:07 AM org.openqa.selenium.remote.ProtocolHandshake createSession
INFORMATION: Detected dialect: OSS
[]
Process finished with exit code 0

javascript java selenium selenium-webdriver xpath

Answer 1

Answer №1

The script

js.executeScript("return nodes =[];");

is the only part being executed, while the rest of the script is disregarded after that return statement. This results in an empty array being returned.

According to the javaDoc documentation for executeScript(String), your script code is enclosed and run as the body of an anonymous function like this:

function f() {
    return nodes = [];
    xPathResult = document.evaluate('//comment()', document, null, XPathResult.ANY_TYPE, null);
    nodes = [];
    node = xPathResult.iterateNext();
    while (node) {
        nodes.push(node.textContent);
        node = xPathResult.iterateNext();
    }
    nodes;
}();

Each script statement is separated by ";". Since the first statement is a return statement, the function ends there and returns the empty array as the result.

In the browser console, the script behaves as expected because it does not halt at the return statement, but rather displays the final value of nodes;.

To correct this issue, you should move the return statement from the first to the last position:

xPathResult = document.evaluate('//comment()', document, null, XPathResult.ANY_TYPE, null);
nodes = [];
node = xPathResult.iterateNext();
while (node) {
    nodes.push(node.textContent);
    node = xPathResult.iterateNext();
}

return nodes;

Answer 2

The script

js.executeScript("return nodes =[];");

is the only part being executed, while the rest of the script is disregarded after that return statement. This results in an empty array being returned.

According to the javaDoc documentation for executeScript(String), your script code is enclosed and run as the body of an anonymous function like this:

function f() {
    return nodes = [];
    xPathResult = document.evaluate('//comment()', document, null, XPathResult.ANY_TYPE, null);
    nodes = [];
    node = xPathResult.iterateNext();
    while (node) {
        nodes.push(node.textContent);
        node = xPathResult.iterateNext();
    }
    nodes;
}();

Each script statement is separated by ";". Since the first statement is a return statement, the function ends there and returns the empty array as the result.

In the browser console, the script behaves as expected because it does not halt at the return statement, but rather displays the final value of nodes;.

To correct this issue, you should move the return statement from the first to the last position:

xPathResult = document.evaluate('//comment()', document, null, XPathResult.ANY_TYPE, null);
nodes = [];
node = xPathResult.iterateNext();
while (node) {
    nodes.push(node.textContent);
    node = xPathResult.iterateNext();
}

return nodes;

Java Selenium Javascript executor fails to return desired result

Answer №1

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