Using HTML DOM to find element always returns error?

Question

I've been having this issue alot today. Every time I use the HTML DOM for finding parts of the page it always returns an error saying "...is not a function."

Everything from printing to the page to even simply changing the page title just fails.

I've used JSLint, looked it up, etc. and still don't have a clue what this means.

What's even more strange is that I easily got it to work on a different page using the same methods. Here was an attempt to create a loading animation for the title bar:

var loadingstat;
loadingstat = false;
var pgtA;
pgtA = 0;
setInterval(pgtUpdater(), 80);
function pgtUpdater() {
    if (pgtA == 0 && loadingstat = true) {
        document.getElementsByTagName[0]("title").innerHTML = "-=-=-";
        ++pgtA;
    } else {
        if (pgtA == 1 && loadingstat = true) {
            document.getElementsByTagName[0]("title").innerHTML = "=-=-=";
            ++pgtA;
        } else {
            if (pgtA == 2 && loadingstat = true) {
                document.getElementsByTagName[0]("title").innerHTML = "-/ \-";
                ++pgtA;
            } else {
                if (pgtA == 3 && loadingstat = true) {
                    document.getElementsByTagName[0]("title").innerHTML = "</ \>";
                    ++pgtA;
                } else {
                    if (pgtA == 4 && loadingstat = true) {
                        document.getElementsByTagName[0]("title").innerHTML = "/   \ ";
                        ++pgtA;
                    } else {
                        if (pgtA == 5 && loadingstat = true) {
                            document.getElementsByTagName[0]("title").innerHTML = "\   /";
                            ++pgtA;
                        } else {
                            if (pgtA == 6 && loadingstat = true) {
                                document.getElementsByTagName[0]("title").innerHTML = "<\ />";
                                ++pgtA;
                            } else {
                                if (pgtA == 7 && loadingstat = true) {
                                    document.getElementsByTagName[0]("title").innerHTML = "-\ /-";
                                    ++pgtA;
                                } else {
                                    if (pgtA == 8 && loadingstat = true) {
                                        document.getElementsByTagName[0]("title").innerHTML = "=-=-=";
                                        ++pgtA;
                                        } else {
                                            if (pgtA == 9 && loadingstat = true) {
                                                    document.getElementsByTagName[0]("title").innerHTML = "-=-=-";
                                                ++pgtA;
                                            } else {
                                                if (pgtA == 10 && loadingstat = true || loadingstat = false) {
                                                        document.getElementsByTagName[0]("title").innerHTML = "-----";
                                                    pgtA = 0;
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

I've never actually had this issue until today. This always seems to happen whenever I try to edit an element in the page.

Also I am aware that these conditions aren't written properly, I'm currently working on fixing that.

To start change loadingstat = true to loadingstat == true. — user7393973
– user7393973, Commented Feb 20, 2018 at 23:00
Then change document.getElementsByTagName[0]("title") to document.getElementsByTagName("title")[0]. — user7393973
– user7393973, Commented Feb 20, 2018 at 23:01

user7393973 · Accepted Answer · 2018-02-20 23:39:40Z

2

Here's a modified version of your code that you can try at about:blank (run the code from the console):

var title = document.getElementsByTagName('title')[0];
if ( !title ) {
  title = document.createElement('title');
  document.head.appendChild(title);
}
var frames = ['-=-=-', '=-=-=', '-/&nbsp;\\-', '</&nbsp;\\>', '/&nbsp;&nbsp;&nbsp;\\', '\\&nbsp;&nbsp;&nbsp;/', '<\\&nbsp;/>', '-\\&nbsp;/-', '=-=-=', '-=-=-', '-----'];
var i = 0;
setInterval(function() {
  title.innerHTML = frames[i];
  if ( i++ == 10 ) i = 0;
}, 500);

answered Feb 20, 2018 at 23:39

user7393973

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1 Comment

bonkmaykr Over a year ago

Works perfect! The conditions used are missing a comparison, something like "loadingstat == true" which is an easy fix, I'll take care of the rest.

Tom · Accepted Answer · 2018-02-20 23:06:34Z

1

You are invoking pgtUpdater() in setInterval. Try just passing the function name. I tried an example function in the console, and as u can see the function is only invoked once when parantheses are used, this could be the issue.

answered Feb 20, 2018 at 23:06

Tom

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