When using JSON.stringify, the output is null. However, when using document.write, the data

I am currently working on a plugin for crawljax that involves executing some JavaScript code, similar to the following:

String result = browser.executeJavaScript(script).toString();

The script code is as follows:

function getElementPosition(id) {
var element = document.getElementById(id);
return JSON.stringify(elementpos(findPosX(element), findPosY(element)));
}

function elementpos(x, y) {
elementpos = new Object();
elementpos.x = x;
elementpos.y = y;
return elementpos;
}


return getElementPosition("foo");

While this seems to run successfully, the result always comes back as null. Strangely enough, if I print out the same data using document.write, I receive a well-formatted JSON string like this:

{"x":8, "y":24}

Could it be that I am misunderstanding something? Is there some issue when dealing with JSON strings and Java? Since I don't have much experience in JavaScript, could it be that I am not permitted to return data in this manner?

I am carrying out these tests on Google Chrome version 25.

Note: I do not believe this problem is related to Crawljax itself since another plugin (written by someone else) utilizes a script that returns a JSON string without any issues...

Answer №1

When it comes to JavaScript, steer clear of new Object();. Instead, opt for a simpler solution like the one provided below:

 return JSON.stringify({x:findPosX(element), y:findPosY(element)});

Avoid using objects created with the new Object(); syntax as they can lead to numerous unexpected issues in JavaScript.

Answer №2

It appears that the issue does not lie with using new Object(), but I welcome any clarification from other commenters. Consider this alternative approach:

function findElementPosition(x, y) {
    var elementPosition = new Object();
    elementPosition.x = x;
    elementPosition.y = y;
    return elementPosition;
}

It's worth noting that adding "var" before "elementPosition = new Object();" is crucial. Without this variable declaration, the initial line of the universal "findElementPosition" function would simply replace itself with an "elementPosition" object. While it may work correctly the first time, subsequent executions could lead to errors as it attempts to interpret the new Object() result as a callable function.

I successfully ran the provided code and converted the output to a string without encountering any issues on Chrome 40. Changing the local variable name from "result" to something distinct from the function name could help eliminate potential confusion in this scenario.

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