Develop Reference

Returned JavaScript value wont render inside a div element

This a basic question (Posting this again, as it was not re-opened after I updated the question). But I couldn't find any duplicates on SO.
This is a script I intend to use in my project on different pages. The purpose is to override the default ID shown in a span element to the order number from the URL parameter session_order. This doesn't affect anything and only enhances the UX for my project.
scripts.js (loaded in the header):
function get_url_parameter(url, parameter) {
var url = new URL(url);
return url.searchParams.get(parameter);
}
And in my HTML template, I call the function this way,
<div onload="this.innerHTML = get_url_parameter(window.location.href, 'session_order');">24</div>
Also tried this,
<div><script type="text/javascript">document.write(get_url_parameter(window.location.href, 'session_order'));</script></div>
When the page is rendered, nothing changes. No errors or warnings in the console either for the first case.
For the second case, console logged an error Uncaught ReferenceError: get_url_parameter is not defined, although script.js loads before the div element (without any errors).
Normally, I'd do this on the server-side with Flask, but I am trying out JavaScript (I am new to JavaScript) as it's merely a UX enhancement.
What am I missing?

Try this:
// This is commented because it can't be tested inside the stackoverflow editor
//const url = window.location.href;
const url = 'https://example.com?session_order=13';
function get_url_parameter(url, parameter) {
const u = new URL(url);
return u.searchParams.get(parameter);
}
window.onload = function() {
const el = document.getElementById('sessionOrder');
const val = get_url_parameter(url, 'session_order');
if (val) {
el.innerHTML = val;
}
}
<span id="sessionOrder">24</span>
Define the function you need for getting the URL param and then on the window load event, get the URL parameter and update the element.

Here you go. Try to stay away from inline scripts using document.write.
function get_url_parameter(url, parameter) {
var url = new URL(url);
return url.searchParams.get(parameter);
}
window.addEventListener('load', function() {
const url = 'https://yourpagesdomain.name/?session_order=hello'; //window.location.href;
const sessionOrder = get_url_parameter(url, 'session_order');
document.getElementById('sessionOrder').innerText = sessionOrder;
});
<div id="sessionOrder"></div>

The order of your markup and script matters...
<div></div>
<script>
function get_url_parameter(url, parameter) {
var url = new URL(url);
return url.searchParams.get(parameter);
}
</script>
<script>
document.querySelector('div').innerHTML = get_url_parameter('https://example.com?session_order=2', 'session_order');
</script>

Running a javascript animation followed by redirecting

So I'm fiddling with a fun idea for an offline website I'm currently trying to develop.
It'll be offline as it's meant to be practice for later study assignments and such.
My problem is the following: I have a javascript function that replaces a PNG with a GIF and after the animation it should redirect the person to another html I've made.
The source for the JS animation is mainly acquired from here already, but I cannot seem to make it work in the ways I originally intended.
The way it currently works is that I click the png and it'll turn into a gif (no problem there) but what I want is that it runs my js script and then redirect to another .html file (url).
The following is my HTML:
<object id="syringe">
<img src="img/syringe.png" height="750" alt="img/syringe.gif" class="center">
<h2>Click the syringe to inject yourself with a daily dose of puns and jokes</h2>
</object>
The following is the JS:
(function($) {
var getGif = function() {
var gif = [];
$('img').each(function() {
var data = $(this).data('alt');
gif.push(data);
});
return gif;
}
var gif = getGif();
var image = [];
$.each(gif, function(index) {
image[index] = new Image();
image[index].src = gif[index];
});
$('#syringe').on('click', function() {
var $this = $(this),
$index = $this.index(),
$img = $this.children('img'),
$imgSrc = $img.attr('src'),
$imgAlt = $img.attr('data-alt'),
$imgExt = $imgAlt.split('.');
if($imgExt[1] === 'gif') {
$img.attr('src', $img.data('alt')).attr('data-alt', $imgSrc);
} else {
$img.attr('src', $imgAlt).attr('data-alt', $img.data('alt'));
}
$this.toggleClass('play');
});
})(jQuery);
It is to my understanding that I can add a delay and then another function to something in the js - such as the following, which is what I intend to do, however cannot accomplish.
[FUNCTION HERE],1000,
function(){
window.location.href=myredirectionuri;
});
And that is my problem.

It looks like you want to have the gif display for a second or two and then redirect, right? If $this.toggleClass('play'); is the end, then just insert this right after it:
setTimeout(() => window.location.href = myredirectionuri, 1000);
That'll wait for 1000ms and then redirect to the new page.

In the animation script, after it changes to a gif, insert
setTimeout(function() {
/* redirect code */
}, /* length of gif in milliseconds */ )

Replacing iframe source with Javascript - Can I use a loop?

I have a list of items (districts) on a page, and an iframe pulling in a map on the same page. When a user clicks on one of the districts, the JavaScript changes the source of the iframe to show a map of the district the user clicked.
My current code simply uses an "onclick" for each district, which then calls a function to change the source of the iframe.
I am wondering if I can simplify this code at all, possibly by using a loop? If I have 15 more districts to add to the page, will I have to add another "onclick" and another function for each one? Or is there an easier way that I am missing?
Simplified HTML:
<div id="districtlist">
Allen
Barren
Butler
<!--about 15 more links to follow-->
</div>
<iframe id="maparea" src="http://www.reddit.com"></iframe>
Javascript:
var a = document.getElementById("districtlist")
a.getElementsByTagName("a")[0].onclick = Allen;
a.getElementsByTagName("a")[1].onclick = Barren;
a.getElementsByTagName("a")[1].onclick = Butler;
//more lines...
function Allen() {
document.getElementById("maparea").src="http://www.youtube.com";
}
function Barren() {
document.getElementById("maparea").src="http://www.mentalfloss.com";
}
function Butler() {
document.getElementById("maparea").src="http://www.amazon.com";
}
//more functions...

I believe you could try this
var elems = document.getElementById("districtlist").querySelectorAll('a');
[].forEach.call(elems, function(elem) {
elem.onclick = function() {
var url = '';
switch(elem.innerText) {
case 'Allen':
url = "http://www.mentalfloss.com";
break;
case 'Barren':
url = "http://www.mentalfloss.com"
break;
case 'Butler':
url = "http://www.amazon.com";
break;
}
document.getElementById("maparea").src=url;
}
});

Creating whole new view based on current user's group sharepoint 2013

I am trying to generate a view based on the current user's group name. Group Name I am gathering from the custom list.
My question is how to apply the gathered group name to 'Group Name' column as a view parameter.
The only solution I figured:
I have created a view with a parameter.
I have added an HTML Form Web Part into the same page and connected it to the list view (sending the value to the parameter via web part connection). Then with a window.onload function I gather the current user's group name and pass this value via Form Postback function. But since the Postback function triggers full page reload, it falls into the endless loop of form submission > page reload.
Another way I have tried is attaching a click event listener to the BY MY GROUPS tab and it works perfectly, but the only disadvantage is that the page reloads each time user clicks on this tab, which I would like to avoid.
So the solution that I need is a way to post the form without a page reload.
Another option suggested here is to use CSR (client side rendering), but that has its own problems:
This code does not work as it is supposed to. In the console it shows me correct items, but the view appears untouchable.
Even if it worked, the other column values are still viewable in the column filter, as in this screenshot:
So, it seems that CSR just hides items from the view (and they are still available). In other words its behavior is different from, for example, a CAML query.
Or am I getting it wrong and there's something wrong with my code?
Below you can find my CSR code:
<script type='text/javascript'>
(function() {
function listPreRender(renderCtx) {
SP.SOD.executeFunc('sp.js', 'SP.ClientContext', function() {
var currUserID = _spPageContextInfo.userId;
var cx = new SP.ClientContext('/sites/support');
var list = cx.get_web().get_lists().getByTitle('Group Members');
var items = list.getItems(SP.CamlQuery.createAllItemsQuery());
cx.load(items, 'Include(_x006e_x50,DepID)');
cx.executeQueryAsync(
function() {
var i = items.get_count();
while (i--) {
var item = items.getItemAtIndex(i);
var userID = item.get_item('_x006e_x50').get_lookupId();
var group = item.get_item('DepID').get_lookupValue();
if (currUserID === userID) {
var rows = renderCtx.ListData.Row;
var customView = [];
var i = rows.length;
while (i--) {
var show = rows[i]['Group_x0020_Name'] === group;
if (show) {
customView.push(rows[i]);
}
}
renderCtx.ListData.Row = customView;
renderCtx.ListData.LastRow = customView.length;
console.log(JSON.stringify(renderCtx.ListData.Row));
break;
}
}
},
function() {
alert('Something went wrong. Please contact developer')
}
);
});
}
function registerListRenderer() {
var context = {};
context.Templates = {};
context.OnPreRender = listPreRender;
SPClientTemplates.TemplateManager.RegisterTemplateOverrides(context);
}
ExecuteOrDelayUntilScriptLoaded(registerListRenderer, 'clienttemplates.js');
})();
</script>

Set og:image and twitter:image meta in wordpress articles with javascript

I'm working on a WP website, and I'm pretty new with code, so after I struggled a whole day to make it work, I just gave up, and decided to ask someone.
I used dynamic meta for all open graphs and twitter cards except image.
All the website pages have a container with an article inside; some articles have an image, and some have none. For the ones with no image, I want to use the Company logo.
So I want to use javascript to add og:image and twitter:image to wordpress, but I can't get over one error that says:
document.getElementsByTagName(" ") is not a function
//add image meta tag
addImageMetaTag();
function addImageMetaTag() {
var imgHolder = document.getElementsByTagName("article")[0];
var image = imgHolder.getElementsByTagName("img");
var source;
function getSource() {
if (image.length != 0) {
var source = image[0].getAttribute("src");
} else {
var source = "http://link_to_my_default_image.png";
}
return source;
};
var meta = document.createElement('meta');
meta.setAttribute("property", "og:image");
meta.content = source;
meta.name = "twitter:image";
document.getElementsByTagName('head')[0].appendChild(meta);
};

Gerald, open graphs and twitter cards are used to create the shared snippet, so it's got nothing to do with crawling.
You were right with your other answer, there were two errors: indeed, I used "getSource" instead of "source", but Wordpress still wouldn't find the "article" class, because the content loads after the header, so I had "var content = undefined", so I got the function working by changing it to this:
// add image meta tag
window.addEventListener("load", function() {
addImageMetaTag();
});
function addImageMetaTag() {
var content = document.getElementById("primary");
var images = content.querySelectorAll("img");
var source;
if (images.length != 0) {
var source = images[0].getAttribute("src");
}
else {
var source = "http://link_to_my_default_image.png";
}
var meta = document.createElement('meta');
meta.setAttribute("property","og:image");
meta.content = source;
meta.name = "twitter:image";
document.getElementsByTagName('head')[0].appendChild(meta);
};