Why is this userscript only doing the first if?

Question

I am working on a User script but it seems to work just for the first comparison:

(function() {
'use strict';

var noError = document.getElementsByClassName("noMistakeButton");
var next = document.getElementsByClassName("nextButton");
var wait = document.getElementsByClassName("understoodButton");
var okko = document.getElementsByClassName("buttonKo");
var exitOkko = document.getElementsByClassName("exitButton");

while(1)
{
    if( noError !== null)
    {
        noError.click();
    }

    if( next !== null)
    {
        exit.click();
    }

    if( wait !== null)
    {
        wait.click();
    }
    sleep(2);
    if( okko !== null)
    {
        exit.click();
    }

    if( exitOkko !== null)
    {
        exitOkko.click();
    }

} })();

My goal is the run this script freely while AFK. There are, as you can see, many buttons on the web page and each button cant be :visible or :hidden. My goal is just to click on them.

Here is the target page (static URL).

Some buttons only have class and no ID. Others have them both.

The console reports:

ERROR: Execution of script 'AutoVoltair' failed! noError.click is not a function

The first `if (...)` is the same as `if (true)` and the code in its block won't do anything but throw an error. — Andreas, Dec 07 '17 at 15:57
"ERROR: Execution of script 'AutoVoltair' failed! noError.click is not a function" the console is telling me that — Maximilien Nowak, Dec 07 '17 at 16:02
Why do you want to do that ? It seems like sort of fraud to me. — Serge K., Dec 07 '17 at 16:04
not fraud, i just want to replace mouse clicking buy scripting! — Maximilien Nowak, Dec 07 '17 at 17:13

score 0 · Accepted Answer · answered Dec 09 '17 at 08:32

It is unclear what you hope to accomplish. If you are trying to step through a sequence of controls, use the approach illustrated in Choosing and activating the right controls on an AJAX-driven site.

The kind of code shown in the question would just play "Whac-A-Mole" with whatever button "popped up" next. (And only if the preceding buttons had been deleted.)

Anyway, to answer the question: "why this code is only doing the first if?".

It's because userscripts (and javascript) stop running at the first critical error ^{(with a few exceptions)}. Additionally:

noError.click is not a function because noError is a collection of elements, not a button.
All the getElementsByClassName calls are only done once. If it's going to continually loop, you need to recheck inside the loop.
There is no such thing as sleep().
while (1) is a very bad idea and can freeze your browser, or even help crash your PC. Use setInterval for polling the page.

Here's the "Whac-A-Mole" code with those errors corrected:

setInterval ( () => {
        var noError     = document.getElementsByClassName ("noMistakeButton");
        var next        = document.getElementsByClassName ("nextButton");
        var wait        = document.getElementsByClassName ("understoodButton");
        var okko        = document.getElementsByClassName ("buttonKo");
        var exitOkko    = document.getElementsByClassName ("exitButton");

        if (noError.length) {
            noError[0].click ();
        }
        if (next.length) {
            next[0].click ();
        }
        if (wait.length) {
            wait[0].click ();
        }
        if (okko.length) {
            okko[0].click ();
        }
        if (exitOkko.length) {
            exitOkko[0].click ();
        }
    },
    222  //  Almost 5 times per second, plenty fast enough
);

If you want to sequence clicks, use chained waitForKeyElements() calls as shown in this answer.

Why is this userscript only doing the first if?

1 Answers1