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Using addEventListener on multiple elements, avoid TypeError when particular element not found

I'm using two simple addEventListener mouseenter and mouseleave functions respectively to play and stop animations (Bodymovin/SVG animations, though I suspect that fact is irrelevant).
So, the following works fine:
document.getElementById('animationDiv').addEventListener('mouseenter', function(){
animation.play();
})
(The HTML couldn't be simpler: The relevant part is just an empty div placeholder filled by script - i.e., <div id="animationDiv"></div>.
I can place that in the same file as the one that operationalizes the animation code, or I can place it in a separate "trigger" file, with both files (and other others necessary to processing) loaded in the site footer.
The problem arises when I need to be able to set triggers for any of multiple similar animations that may or may not appear on a given page.
If only one of two animatable elements are present on a page, then one of two sets of triggers will throw an error. If the first of two such triggers is not present, then the second one will not be processed, meaning that the animation will fail. Or at least that's what it looks like to me is happening.
So, just to be clear, if I add the following two triggers for the same page, and the first of the following two elements is present, then the animation will play on mouseenter. If only the second is present, its animation won't be triggered, apparently because of the error thrown on the first.
document.getElementById('firstAnimationDiv').addEventListener('mouseenter', function(){
firstAnimation.play();
})
document.getElementById('secondAnimationDiv').addEventListener('mouseenter', function(){
secondAnimation.play();
})
At present I can work around the problem by creating multiple trigger files, one for each animation, and setting them to load only when I know that the animatable element will be present, but this approach would get increasingly inefficient when I am using multiple animations per page, on pages whose content may be altered.
I've looked at try/catch approaches and also at event delegation approaches, but so far they seem a bit complicated for handling this simple problem, if appropriate at all.
Is there an efficient and flexible standard method for preventing or properly handling an error for an element not found, in such a way that subsequent functions can still be processed? Or am I missing something else or somehow misreading the error and the function failure I've been encountering?
WHY I PICKED THE ANSWER THAT I DID (PLUS WORKING CODE)
I was easily able to make the simple, directly responsive answer by Baoo work.
I was unable to make the answers below by Patrick Roberts and Crazy Train work, though no doubt my undeveloped js skills are entirely at fault. When I have the time, or when the issue next comes up for me in a more complex implementation (possibly soon!), I'll take another look at their solutions, and see if I can either make them work or if I can formulate a better question with fully fledged coding examples to be worked through.
Finally, just to make things clear for people who might be looking for an answer on Bodymovin animations, and whose js is even weaker than mine, the following is working code, all added to the same single file in which a larger set of Bodymovin animations are constructed, relieving me of any need to create separate trigger files, and preventing TypeErrors and impaired functionality.
//There are three "lets_talk" animations that can play - "home," "snug," and "fixed"
//and three types of buttons needing enter and leave play and stop triggers
let home = document.getElementById('myBtn_bm_home');
if (home) home.addEventListener('mouseenter', function() {
lets_talk_home.play();
});
if (home) home.addEventListener('mouseleave', function() {
lets_talk_home.stop();
});
let snug = document.getElementById('myBtn_bm_snug');
if (snug) snug.addEventListener('mouseenter', function() {
lets_talk_snug.play();
});
if (snug) snug.addEventListener('mouseleave', function() {
lets_talk_snug.stop();
});
let fixed = document.getElementById('myBtn_bm_fixed');
if (fixed) fixed.addEventListener('mouseenter', function() {
lets_talk_fixed.play();
});
if (fixed) fixed.addEventListener('mouseleave', function() {
lets_talk_fixed.stop();
});
At typical piece of underlying HTML (it's generated by a PHP function taking into account other conditions, so not identical for each button), looks like this at the moment - although I'll be paring away the data-attribute and class, since I'm not currently using either. I provide it on the off-chance that someone sees something significant or useful there.
<div id="letsTalk" class="lets-talk">
<a id="myBtn" href="#"><!-- a default-prevented link to a pop-up modal -->
<div class="bm-button" id="myBtn_bm_snug" data-animation="snug"></div><!-- "snug" (vs "fixed" or "home" is in both instances added by PHP -->
</a>
</div>
Obviously, a more parsimonious and flexible answer could be - and probably should be - written. On that note, correctly combining both the play and stop listeners within a single conditional would be an obvious first step, but I'm too much of a js plodder even to get that right on a first or second try. Maybe later/next time!
Thanks again to everyone who provided an answer. I won't ask you to try to squeeze the working solution into your suggested framework - but I won't ask you not to either...

Just write your code so that it won't throw an error if the element isn't present, by simply checking if the element exists.
let first = document.getElementById('firstAnimationDiv');
if (first) first.addEventListener('mouseenter', function() {firstAnimation.play();});

You could approach this slightly differently using delegated event handling. mouseover, unlike mouseenter, bubbles to its ancestor elements, so you could add a single event listener to an ancestor element where every #animationDiv is contained, and switch on event.target.id to call the correct play() method:
document.getElementById('animationDivContainer').addEventListener('mouseover', function (event) {
switch (event.target.id) {
case 'firstAnimationDiv':
return firstAnimation.play();
case 'secondAnimationDiv':
return secondAnimation.play();
// and so on
}
});
You could also avoid using id and use a more semantically correct attribute like data-animation as a compromise between this approach and #CrazyTrain's:
document.getElementById('animationDivContainer').addEventListener('mouseover', function (event) {
// assuming <div data-animation="...">
// instead of <div id="...">
switch (event.target.dataset.animation) {
case 'first':
return firstAnimation.play();
case 'second':
return secondAnimation.play();
// and so on
}
});

First, refactor your HTML to add a common class to all of the placeholder divs instead of using unique IDs. Also add a data-animation attribute to reference the desired animation.
<div class="animation" data-animation="first"></div>
<div class="animation" data-animation="second"></div>
The data- attribute should have a value that targets the appropriate animation.
(As #PatrickRobers noted, the DOM selection can be based on the data-animation attribute, so the class isn't really needed.)
Since your animations are held as global variables, you can use the value of data-animation to look up that variable. However, it would be better if they weren't global, but were rather in a common object.
const animations = {
first: null, // your first animation
second: null, // your second animation
};
Then select the placeholder elements by class, and use the data attribute to see if the animation exists, and if so, play it.
const divs = document.querySelectorAll("div.animation");
divs.forEach(div => {
const anim = animations[div.dataset.animation];
if (anim) {
anim.play(); // Found the animation for this div, so play it
}
});
This way you're guaranteed only to work with placeholder divs that exist and animations that exist.
(And as noted above, selection using the data attribute can be done const divs = document.querySelectorAll("div[data-animation]"); so the class becomes unnecessary.)

Web Animations API: reset animation on demand

I have a complex animation as a combination of KeyframeEffect's grouped into GroupEffect and SequenceEffect. In a very simplified version it looks something like presented in this JSBin https://jsbin.com/denucaq/edit?html,js,output
The problem is that I have to reset all the changes done by animation at some point in order to, possibly, re-run the animation or do something else.
I can not use fill: 'none' since different elements animate with different durations and they all have to stay in it's final position until all the elements have been animated.
So the questions is what should I write in the body of the crazyWords.reset function?

It's going to require a bit of math, but you can get all the info you need from the methods themselves. Try putting this inside the reset function then clicking it at various times:
console.log(document.timeline);
You have access to a oncancel method, so you can use that to revert the changes based on the start time versus the current time, and so forth (maths happening here). I also just found a reverse method that works nicely:
const allAnimations = document.timeline.getAnimations();
allAnimations.forEach((ani) => {
ani.pause();
console.log(ani.playState);
ani.reverse();
});

How to harness control of my JQuery coded sliding divs?

Essentially I have 4 divs that take turns sliding in and sliding out with delays and then it recalls the function. Like so:
$(document).ready (function bradslide(){
$("#slide1").delay('1000').slideDown('1000').delay('6000').slideUp('1000');
$("#slide2").delay('9000').slideDown('1000').delay('6000').slideUp('1000');
$("#slide3").delay('17000').slideDown('1000').delay('6000').slideUp('1000');
$("#slide4").delay('25000').slideDown('1000').delay('6000').slideUp('1000', 'swing', bradslide);
}
);
Let me say that this works fine, but that I am open to cleaning it up or making it easier or more up to standard if suggestions are made.
However my question is this: How can I arrange this so that the end user can manipulate the animation. This slides through the divs on its own, but ideally I would like to have a couple buttons to click to go backward or forwards (I think you get the idea).
Any suggestions of how or where to begin would be greatly appreciated. I imagine I might have to scrap this little piece of code as it stands. Thanks in advance guys.

Despite my own comment, I do have some general advice:
Look into using classes instead of IDs, and then use jQuery's DOM-traversal methods to identify what the next slider candidate is. Tracking the "currentSlide" and then targeting the "nextSlide" (identified with a .next() perhaps?) means that you can add any number of slider divs (with a class instead of ID, remember?) and still have it work.
The user controls (next, prev, or selecting a specific slide) simply interrupt the timer (probably a setTimeout instead of .delay()) and then invoke the exact same function that brings the next slide into place.
To make code more reusable and flexible, you should use some variables. For example, if your slide duration is going to be 1000, you would have var duration = 1000 scoped to an appropriate place (the document ready function is fine... or the sliding function) and then in your function call (whatever it ends up looking like), you would use .slideDown(duration). Then you can set that value to whatever you want and update it easily later.
Extending on the above, you could even build an API allowing you to pass values into your custom slider function:
var bradslide = function(container, delay, duration) {
// do stuff with a parent container, some delay value, and a duration value
};
bradslide('sliderParent', 6000, 1000);

Trying to fix table header, getting css issue

Initially I asked this Question and written my own plugin to achieve the same,But i am facing very strange issue regarding to css of table.
After applying the plugin table cells borders are getting dis-sorted.
jsFiddle of the problem: Problem demo
In fiddle you can see that after first cell of the first tr, the header border line and table border line don't line up. I want the border line of thead cells and td cells to line up.
Can anyone tell me how to achieve that?

Lets start by doing a bit of a clean up of the code you posted so I can actually read your code and maintain a firm grasp on reality while we go down this rabbit hole.
If you write clean code, your problems will be exceptionally easier to see.
So lets clean it up and watch as all the problems here reveal themselves.
Step one: Your jsFiddle sets it to run "onDomReady," which basically means you've got $(document).ready(...) calling all the code in the box, which is fine, except you're got another got $(document).ready(...) inside there. Lets change that.
Step two: Lets add some white space and proper indentation in there, and stop using these one letter variable names.
{} are scope brackets, they should indent, not cover everything, they let us know what part of scope something is in.
Don't write .each() loops on one line, this adds no value and makes your code confusing to read.
$t should be called something meaningful, lets try element, because it holds the $(this) element, which is the active element you're working with.
w should be called something meaningful, but since you only use it twice I'm just going with element.width().
o needs to be less ambiguious, lets go with obj.
Step three: Selection structures
if(typeof(i)=='number')o.height=i;
else if(typeof(i)=='object')o=i;
else if(typeof(i)=='undefined')o={height:300}
Break that up, make it readable. Saving lines doesn't make you a better program, writing clean and easily understandable code will.
Why not use the switch-case statement?
switch (typeof(i)){
case "number":
o.height=i;
break;
case "object":
o=i;
break;
case "undefined":
o={height:300};
break;
}
Step four: Don't in-line styles. Just don't. There's no reason to do it, and it makes everyone's life harder.
Instead, lets just place the styles gently into the style sheet where it belongs, and make the parent=$('...') line look like parent=$('<div><div></div></div>').appendTo('body');.
Step five: Closure doesn't pass any value to arguments
After a bit of clean up, we see this block of code:
self.width(self.width() -
function(width){
var parent,child;
if(width===undefined){
parent=$('<div><div></div></div>').appendTo('body');
child=parent.children();
width= (child.innerWidth()) - (child.height(99).innerWidth());
parent.remove();
}
return width;
}()
);
Okay, that's a problem. Lets cut out a few lines to point out the problem here:
self.width(
self.width() -
function(width){
/*...*/
if(width===undefined){
/*...*/
}
return width;
}()
);
So, a quick refresher on this pattern you have here:
(function(arg1){
/*code*/
})(data);
Data gets passed to arg1. Arg1 declaires a variable in the scope local to that function, it doesn't get anything from outside. Outside data is passed in through the set of () that call the function, which your code had left abandoned. Think of it this way:
var msg = function(text) {
alert(text);
};
Then you call it as...
msg("hello world");
What your closure is doing is almost the same thing, except where you define your function, you also call it. Thus...
(function(text) {
alert(text);
})("hello world");
So, you need to pass a value of some sort into there, other wise this whole thing is always undefined. Lets do that. What are we passing? I have no way to be sure. This is why programmers need to add comments to their code.
Step six: Comment your code so people other than yourself will look at this code and have not a damn clue what you truthfuly wanted to do, and can only guess. It's like you posted a 200 point bounty and didn't bother helping people who want to help you. Why are you doing this to yourself, dude? Why couldn't you just go //This is what this does to give me a hint? What did I ever do to you?
Step Seven: Lets see if we can make the JS changes work with the JS Fiddle
Great odin... that HTML's 2000 lines long?
Okay, I'm working with pastebin here for the sake of saving space in the post here.
Alright, you started off with this: http://pastebin.com/xjmm4cev
You're using a lot of no-wrap, and putting classes onto individual elements. You shouldn't have to do this on each HTML element, CSS takes care of that very effectively, so lets go ahead and just rip out all the nowrap=nowrap and class="header" stuff (we'll put it back in a moment, but only ONE per group, not each element).
Then lets get rid of the useless blank lines.
Lets run this through HTML tidy and get it nice and indented correctly.
http://pastebin.com/uHtSZ4h5
Much easier to read over. Okay, so what do we see here? Well, it looks like you keep going in circles, cutting and pasting the same thing again and again. You also in-line javascript such as using onchange and onclick attributes. This is generally an awful thing to do to your code, and makes it hard to maintain (as I'm sure you've seen with this 2000+ line beast of cut+paste 27 times in a row).
So, lets take a look here:
elements, not inside a form
Elements in a table that are outside of rows, but not head/body/footer sections of a table
Code that's a huge pain to maintain because it keep going in circles, if you need to change this, you're basically screwed.
Lets fix all that.
We're going to use events in the tags, rather than in-line things. So, all of those in-line onchange and click attributes get the boot.
All of these inputs that are just floating around need to get put into a form, and taken out of this place in tables that only rows or table sections belong in.
Figure out how we can not have excessive input elements, if we can help it.
What the heck is the )="" that you have on every input button? Deleted.
So, here's all of your hidden boxes: http://pastebin.com/LXZSkvyf which I've removed, because we don't have a anywhere.
And here's what the code looks like without all of these weird things in it: http://pastebin.com/MiaJTGpb
Much more readable, but still not quite there.
Step 8: What can you do to make the HTML of the table work better?
You're using Thead and Tbody, and that's good.
You're using attributes for things like cellpadding, that's bad.
You've given each body row an ID. I don't feel you needed to do this, but it's not always bad. However, I'll show you how you could work without it.
You give some selects a select-box class, but it's nowhere in the css. I've removed it.
You give a title attribute to the selects that says "option_value". The title attribute is generally used to make a tool-tip popup when you leave the mouse over something. I'm not sure what you're going to do here, but that's bound to confuse your user. I'd highly suggest giving something better than option_value in that place.
You keep using the ID Submit_FMS_AddDelivery. HTML ID tags are meant to be unique, and used only once on one element. You've got it 27 times, that's bad. I don't think you need an ID on it, so I've removed it.
You've also got input-btn going on, I'm removing it, because you haven't shown it's used anywhere.
You probably don't need any of these ID tags on select and TR to be honest, so I'm pulling them.
What's that look like? Basically, you've got what's almost just the data, in it's nice pure form. That's good. http://pastebin.com/UNS6CAtb
Step 9: What were you trying to do?
Lets step back and take a look here.
All you really wanted to do was keep a fixed header, but you've ended up doing a lot of JavaScript hacks and manipulating the DOM in a lot of places. We need to stop doing this. Is there a simpler way to do what you want?
I'll have to expand on how to make this function with the rest of your stuff, but I get up for work in a few hours. I'll update again with more... But we'll get there.
Right now, because I haven't fixed what I took out, it doesn't look right. But I'm tired.
So, here's where we are so far: http://jsfiddle.net/5C6z7/
Plus those inputs we took out (and will be going back in later, in a different way)

Looks like all you have to do is to take the padding into account: each cell has 3 px padding both left and righ so you have to add 6 px to the width:
$t.find('tr:first th').each(function(){cols.push($(this).width()+6);});
Otherwise the cells with only one word inside will "push" the actual width a bit wider so that the word will fit and other cells with space to move will compensate by becoming a bit narrower. The header and the body both do this independently with different contents which creates the difference in actual cell widths.
EDIT: For Firefox you also need to widen the table so that the cells fit. After calculating the column widths add
var actualWidth = $t.width()+cols.length*6;
$t.width( actualWidth );
And later change the wrapper to:
$wrap.css({width:actualWidth,height:o.height,overflow:'auto'});
EDIT 2: To have both the header and the body scroll simultaneously you need to wrap them both to an outer div that handles the scrolling.
var $outerWrap = $( '<div>' ).css( {width:"300px", overflow:'auto' } );
var $wrap=$('<div>').css(
{ width:actualWidth,height:o.height,"overflow-y":'auto', "overflow-x":'hidden' }
);
$firstRow.wrap( $outerWrap );
$firstRow.after( $wrap );
$wrap.append( $t );
Demo: http://jsfiddle.net/YcRTz/2/

What about replacing '<th>' tags with '<td>' tags?
No extra js code required.
http://jsfiddle.net/spQAh/7/

Okay so instead of troubleshooting or using anything complex, I came up with simple CSS + JS solution to your problem. Take a look at http://jsfiddle.net/TdLQT/
Obviously, the process of making header static, can be made dynamic, meaning trigger it after user scrolls a bit or have it there by default or count other object's position from top window and trigger static behavior when it reaches or exceeds certain pixels. I can provide that if you give me details on exact design of your HTML page.
Anyways, I as you can see, have used fixed pixel heights which you can choose not to or make them elastic or dynamic. What is important to know is that, though solution relies on JS a bit, output position is purely from CSS. I am using classes to manipulate the position.

the simple solution is that when you calculate the width of the column you do not include padding. So you need to change the line
$t.find('tr:first th').each( function() {
cols.push($(this).width());
});
to
$t.find('tr:first th').each( function() {
cols.push($(this).outerWidth());
});
if your cells have margins use .outerWidth(true)
This works in quirks mode with IE7&8 and Chrome IE8 has a problem in strict mode. However I believe that that problem is caused by the added scrollbar. If you want to use IE8 in strict mode you have to allow for the width of the vertical scrollbar..

jquery ui.slider: add click event to display/hide handle

I am completely new to javascript and jquery. My programming knowledge is... nonexistent, I just started some days ago with some simple tasks like replacing a CSS class or toggling a div. So I want to apologize if I'm treading on someones toes by asking newbie-questions in here. But I hope that someone can help me and solve my problem.
I need to implement some sort of visual analog scale for a survey; ui.slider is perfect for that one. But I need the handle to be hidden by default. When the user clicks on the slider, the handle shall appear in the proper position. That should be fairly simple - at least I hope so - by just hiding the handle with CSS and changing it by a click event on the slider.
I use the following piece of code to wrap a normal div (a div is needed in my understanding to apply the jquery slider.js) to my input elements (they should be - at least visually - replaced by the slider) and pass the value of the slider to the input elements (needed for passing the values to a form). that works properly. (I do that instead of just putting a div in my DOM by default because I cannot influence some PHP scripts that will generate form elements of the survey and so on)
$(function () {
$.each($('.slider'),
function () {
obj = $(this);
obj.wrap('<div></div>');
obj.parent().slider({
change: function (event, ui) {
$('input', this).val(ui.value);
}
});
});
});
Hiding the slider-handle can be done by CSS as described above by changing style properties of a.ui-slider-handle. but when I add a normal click event to the slider (.ui-slider) that changes CSS properties of the handle, nothing happens. As far as my basic knowledge goes it should have something to do with the click event not working on generated DOM elements. Am I right with that one? And if yes: how can I solve this problem? Could someone provide me a piece of code for my function and explain it so I might comprehend what's exactly going on?
I read a tutorial about events on learningjquery.com but I have not made enough progresses the last few days since I started working with JS/jquery to comprehend the steps and translate it into my example/problem. And I am running out of time (I need this for a survey I have to make asap, that's why I hope someone could give me a hint so I can solve this little issue somehow).

Any reason you can't just include the show on the change event rather than a click? It's a bit cleaner code-wise rather than including a whole new event.
$(function() {
$('.slider').wrap('<div></div>').parent().slider({
change: function(event, ui) {
$('input', this).val(ui.value);
$('.ui-slider-handle').show();
}
});
});
Also, there was a bit of redundancy in the code - most jQuery functions return the object itself, so you can chain them. And you don't need that each function, since most jQuery functions also, when applied to a collection, run on all of them :)