driver.executeScript() 为简单的 javascript 返回 NullPointerException
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driver.executeScript() returns NullPointerException for simple javascript
提问by Sudhakar
js.executeScript("return document.title")works fine as expected but I'm not sure why my code returns null pointer error. what is wrong here?
js.executeScript("return document.title")按预期工作正常，但我不确定为什么我的代码返回空指针错误。这里有什么问题？
String testJs= "function test() {arr = 111; return arr;}; test();";
JavascriptExecutor js = (JavascriptExecutor) driver;
int a = (Integer) js.executeScript(testJS);
采纳答案by Sotirios Delimanolis
This javascript
这个javascript
function test() {arr = 111; return arr;};
test();
Calls the method test()but doesn't do anything with the result, ie. doesn't return it to the caller.
调用方法test()但不对结果做任何事情，即。不会将其返回给调用者。
So
所以
int a = (Integer) js.executeScript(testJS);
will return nulland try to be dereferenced which will fail because dereferencing nullthrows NullPointerException.
将返回null并尝试取消引用这将失败，因为取消引用nullthrows NullPointerException。
Javadocfor JavascriptExecutor.html#executeScript(java.lang.String, java.lang.Object...)
Javadoc用于JavascriptExecutor.html#executeScript(java.lang.String, java.lang.Object...)
Maybe you want the javascript
也许你想要 javascript
function test() {arr = 111; return arr;};
return test();
This works for me
这对我有用
System.setProperty("webdriver.chrome.driver", "C:\Users\me\Downloads\chromedriver.exe");
ChromeDriver driver = new ChromeDriver();
JavascriptExecutor executor = (JavascriptExecutor) driver;
String js = "function test() {" +
"arr = 111; return arr;" +
"}; return test()";
Long a = (Long) executor.executeScript(js);
System.out.println(a);
回答by Andrii Bogachenko
Yeah, the key thing is not to forget insert the return, f.e.:
是的，关键是不要忘记插入return，fe：
Long dateNow = (Long) jse.executeScript("return Date.now()");
