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Why does setting objectPosition cause my JavaScript to crash?

Style objectPosition Property gives this example of setting objectPosition:
document.getElementById("myImg").style.objectPosition = "0 10%";
However, when I try to set objectPosition it causes my JavaScript to crash.
In the following code I use CSS to set objectPosition like this:
#img1 {
object-position: 0 0;
width: 635px ;
height: 580px ;
}
Near the bottom of function getImg, my debug code (the “insert” statement) shows it set to “0px 0px”. However, if I proceed this with
imgStyle.objectPosition = "0 0";
The “insert” statement and all following statements are not executed. Here’s my full code with the offending statement commented out:
"use strict";
const numberOfFigures = document.getElementsByTagName('figure').length;
const scale = 3; // scaling up factor
// The function "insert" is used purely for debug purposes
function insert(figNum) {
document.getElementById("para").innerHTML = "OK so far" + figNum;
}
// Create all thumbnails & big images.
for (let i = 0; i < numberOfFigures; i++) {
getImg(i + 1);
}
function getImg(figNum) {
// Create the thumbnails and big images
let startPosn = "0px"; // x-coordinate of object-position for thumbnail
var btnDiv = document.createElement('div');
btnDiv.setAttribute("id", "bigImg" + figNum);
btnDiv.style.backgroundColor = "white";
// Get the figure caption
const figcap = document.getElementById("fig" + figNum).firstElementChild;
btnDiv.innerHTML =
'<button type="button"' +
'class="displayBtn"' +
'onclick="hideBigImg (' +
figNum +
')">Hide large image</button>';
const btnPtr = figcap.appendChild(btnDiv);
/* Append the button to the
figcaption */
var imgDiv = document.createElement('div');
imgDiv.setAttribute("id", "imgDiv" + figNum);
if (figNum === 1) {
/* First image needs height: 100vh or only the top slice is
displayed. Other images may be messed up if this is applied to
them. */
imgDiv.innerHTML = '<' + 'img id="img' + figNum + '" ' +
'class = "sprite-img" ' +
'src="bates-sprite.jpeg" ' +
'style="height: 100vh; ' +
'transform-origin: top left; ' +
'transform: scale(' +
scale + ');">';
} else {
imgDiv.innerHTML = '<' + 'img id="img' + figNum + '" ' +
'class = "sprite-img" ' +
'src="bates-sprite.jpeg" ' +
'style="transform-origin: top left; ' +
'transform: scale(' +
scale + ');">';
}
const imgPtr = btnPtr.appendChild(imgDiv);
/* Append the img to the
button */
/* Make imgDiv high enough to hold the scaled up image & make the
accompanying text visible.
IMPORTANT to do this AFTER creating & appending the. */
// Get the height and width of the image
let img = document.getElementById("img" + figNum);
const imgStyle = getComputedStyle(img);
// Set imgDiv to exactly hold image
imgDiv.style.width = parseInt(imgStyle.width) * scale + "px";
imgDiv.style.height = parseInt(imgStyle.height) * scale + "px";
imgDiv.style.overflow = "hidden"; // Clip off rest of sprite
/*********************** Create thumbnail here *************/
let thumbHTML = '<' + 'div id="thumbDiv' + figNum + '" ' +
'onclick = "showBigImg(' +
figNum + ')" ' +
'style="float: left; ' +
'height: imgStyle.height; ' +
'width: imgStyle.width; ' +
'margin-right: 1.5em; ' +
'background-color: white; ' +
'border: thick solid black;"> ' +
'<' + 'img id="img' + figNum + '" ' +
'class = "sprite-img" ' +
'src="bates-sprite.jpeg" ' +
'style="transform-origin: top left; ' +
'transform: scale(0.5);" ' +
'onclick = "showBigImg(' +
figNum + ')";>' +
'</div>';
figcap.insertAdjacentHTML("afterend", thumbHTML);
/* Append the
thumbnail to the
figcaption */
/* Shrink the div to match the size of the thumbnail, and free up all the
blank space which the full size image would have occupied if it hadn't
been reduced with transform: scale */
let thumbnail = document.getElementById("thumbDiv" + figNum);
thumbnail.style.width = parseInt(imgStyle.width) / 2 + "px";
thumbnail.style.height = parseInt(imgStyle.height) / 2 + "px";
// Set object-position for image in sprite
//imgStyle.objectPosition = "0 0";
insert(imgStyle.objectPosition);
hideBigImg(figNum);
}
function showBigImg(figNum) {
document.getElementById('bigImg' + figNum).style.display = 'block';
document.getElementById('thumbDiv' + figNum).style.display = 'none';
}
function hideBigImg(figNum) {
document.getElementById('bigImg' + figNum).style.display = 'none';
document.getElementById('thumbDiv' + figNum).style.display = 'block';
}
/* Global constants */
:root {
--shrink: 0.30;
/* Size compressed to 30% */
}
figure {
display: block;
width: 96%;
float: left;
border-width: thin;
}
figcaption {
background-color: yellow;
}
.sprite-img {
background-repeat: no-repeat;
object-fit: none;
}
#img1 {
object-position: 0 0;
width: 635px;
height: 580px;
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="general.css">
</head>
<body>
<figure id="fig1">
<figcaption>Camberley Mail</figcaption>
<p id="para">Text to go with picture.</p>
</figure>
</body>
</html>

The reason why the program 'crashes' or more specifically throws an Exception is because you are trying to modify the properties of a read-only object.
In detail:
const img = document.querySelector("img");
const imgStyle = getComputedStyle(img); // imgStyle is a read-only object
imgStyle.objectPosition = "0 0";
The above code will throw:
Uncaught DOMException: Failed to set the 'object-position' property on 'CSSStyleDeclaration': These styles are computed, and therefore the 'object-position' property is read-only.
As stated in the MDN documentation:
"The object from getComputedStyle is read-only, and should be used to inspect the element's style — including those set by a element or an external stylesheet.
The element.style object should be used to set styles on that element, or inspect styles directly added to it from JavaScript manipulation or the global style attribute."
So, based on the docs, you should use the element.style object for setting the properties:
img.style.objectPosition = "0 0";

how to add values of textshadow in javascript

I really want long shadows in Javascript but I dont want to code every single one line of them ,so i thought automize it so it works something like this :
for (let i = 0; i < length; i++) {
document.getElementById("text").style.textShadow = i + "px" + ' ' + i + "px" + ' ' + 0 + ' ' + color
}
The problem is it doesn't work. I also tried it with arrays with no luck, the only real working thing is to code every single one of the shadows, but I want an adaptable solution.
How can I try and implement it?

You just need to use an array here to add all shadow variables and then join them as a comma-separated string to get the desired output like:
const color = '#696767';
let shadow = []
for (let i = 0; i < 40; i++) {
shadow.push(i + "px" + ' ' + i + "px" + ' 0 ' + color)
}
document.getElementById("text").style.textShadow = shadow.join(',')
#text {
letter-spacing: 0.5rem;
font-size: 3rem;
margin-top:0
}
<h1 id="text"> HELLO WORLD </h1>

How to successfully execute a callback on an async method

I am currently trying to return a value from a function that contains an async function and I'm stuck.
I am currently working with SharePoint 2013 JSOM to extract the email address from a Person column. I have found a nice function that does this and I elected to pass the userID into the function.
The function itself contains console.log and outputs the expected result, however, I need those results up where I called the function from in the first place so I found that I need to use a callback. I cannot extract a variable from the calling method.
var t = oListItem.get_item('ElementContactFullName').get_lookupId();
var q = getEmail(t, function(returnedValue){});
function getEmail(userId, callback) {
var x = [];
var context = new SP.ClientContext();
var web = context.get_web();
var user = web.get_siteUsers().getById(userId);
context.load(user);
context.executeQueryAsync(function() {
//console.log(user.get_email());
var y = user.get_email();
x.push(y);
}
, function() {
console.log("error");
});
callback(x);
}
What I want is q to equal the email address so I can use it elsewhere in the calling function.
What I get is "Undefined" no matter what I try.
I can place console.log in function(returnedValue){}) but that still doesn't let me get at the variable. Not done enough JScript to understand the very complex dicussions on the proposed duplicate.

function getEUEmail(userId, JT, flag, callback) {
var x = [];
var contextEU = new SP.ClientContext();
var web = contextEU.get_web();
var user = web.get_siteUsers().getById(userId);
contextEU.load(user);
contextEU.executeQueryAsync(function() {
//console.log(user.get_email());
var y = "<div class='tablewrapper'>" +
"<div class='table'>" +
"<div class='row'>" +
"<div class='rowspanned cell'>" +
' <img class="contacts" src="' + _spPageContextInfo.webServerRelativeUrl + '/_layouts/15/userphoto.aspx?size=M&accountname='+ user.get_email() +'"/>' +
"</div>" +
"<div class='cell'>" +
user.get_title() +
"</div>" +
"</div>" +
"<div class='row'>" +
"<div class='empty cell'></div>" +
"<div class='cell'>" +
JT +
"<div class='cell'>" +
' <img class="flag" src="' + window.location.protocol + "//" + window.location.host + '/SiteAssets/Images/'+ flag +'.png"/>' +
//http://staging.intranet.ent.sys.element.com/SiteAssets/Images/EU.png
"</div>" +
"</div>" +
"</div>" +
"</div>" +
"</div>"
x.push(y);
callback(x);
}
Then to use it
getEUEmail(t,u, v, function(returnedValueEU) {
//console.log(returnedValue[0])
$("#divListItemsEU").append(
"<style type='text/css'> .tablewrapper { position: relative; box-sizing: border-box; height:72px} .table {display: table; } .row { display: table-row; padding: 1px; } .cell { display: table-cell; border: none solid red; padding: 3px;} .cell.empty { border: none; width: 75px; } .cell.rowspanned { position: absolute; top: 0; bottom: 0; width: 75px; display: block; margin: 1px;} .contacts{ width: 72px; height: 72px;} .flag { width: 30px; height: 20px; }</style> " +
"" + returnedValueEU[0] +
'<br />');
});
$("#divListItemsEU").html(listEUItemInfoEU);
}
I ended up passing all the values into the getEmail function, building the HTML then worked out how to leverage the callback with some help. Probably not correct, efficient or elegant but it works. Thanks

How to add a line break in oldschool javascript div

I have to alter the following code somehow to add line breaks to the labels on the buttons generated by AddRemoteButtonText. Tried everything I found on this site, but nothing worked yet (most probably because I`m just starting out coding javascript). Mostly tried adding another variable to the function and then implementing it by "\n" .
var size = 20;
var repeat_timer;
function AddRemoteButtonText(num, posx, posy, wx, wy, color, label, remote, command, initial_delay, repeat_delay)
{
document.write('<div id="' + num + '" class="button ' + color + '" style="position:absolute; top:' + posy + 'px; left:' + posx + 'px; height:' + wy + 'px; width:' + wx + 'px; line-height: ' + wy + 'px;" align="center">' + label + '</div>');
document.getElementById(num).onmouseup = function () { SendIRCommand (num,remote,command,initial_delay,repeat_delay); EndSendCommand (num) };
document.getElementById(num).onmouseleave = function () { EndSendCommand (num) };
}
}
};
Thanks for your answer!

Add '<br>' like in the below example
document.write(variable +'<br/>'+ variable2);

I would probably do it like this (simplified for example purposes):
var i = 0;
var aboveLineBreak;
var belowLineBreak;
function AddRemoteButtonText() {
console.log(i);
//define some text to print to the button
aboveLineBreak = "above br" + i;
belowLineBreak = "below br" + i;
//create a button object
var btn = document.createElement("DIV");
//add our text, including the line break, to the button
btn.appendChild(document.createTextNode(aboveLineBreak));
btn.appendChild(document.createElement("BR"));
btn.appendChild(document.createTextNode(belowLineBreak));
//define our button's CSS style
btn.setAttribute("class", "button red");
//to set the position, do:
//btn.style.position = "absolute";
//btn.style.top = whatever;
//and so on...
//add listeners if needed...
btn.onmouseup = function () { console.log("foo"); };
//finally add the button to the document's body and increment i
document.body.appendChild(btn);
i++;
}
.button {
width: 33%;
height: 45px;
}
.red {
background-color: darkred;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<button onClick="AddRemoteButtonText();"> Add Remote Button Text </button>
</body>
</html>
Not the most beautiful buttons, but if you simply substitute my CSS with your own you should have a working line break. If not, we will need you to post your CSS so we can have a look at it.

How to wrap divs inside a new div?

I'm trying to wrap the two divs <div class="cm-cp-title"> and <div class="cm-cp-value"> inside a div called cm-cp-container. Actually it is working, but it merges all together, it is shown like below after I put the wrapAll();
what is that issues? im wonder how to separate each of it?
Below is the result i needed,
$(function() {
// document
'use strict';
var coupon = $('div.cm-coupon');
// Settings
coupon.each(function() {
var _coupon = $(this);
var cpValue = _coupon.attr("data-value") + "";
// Different Data type
if (_coupon.data('type') == "c1")
{
_coupon.addClass('red').css(
{
"background" : "black",
"display": "table"}
);
_coupon.append(
'<div class="cm-cp-title">' + 'black here' + '</div>' + '\n' + '<div class="cm-cp-value">' + cpValue + '</div>'
);
}
else if (_coupon.data('type') == "c2")
{
_coupon.addClass('green').css(
{
"background" : "green",
"display": "table"}
);
_coupon.append('<div class="cm-cp-title">'+ 'green here' + '</div>' + '\n' + '<div class="cm-cp-value">' + cpValue + '</div>');
}
else if (_coupon.data('type') == "c3")
{
_coupon.addClass('blue').css(
{
"background" :"blue",
"display": "table"}
);
_coupon.append('<div class="cm-cp-title">'+ 'blue here' + '</div>' + '\n' + '<div class="cm-cp-value">' + cpValue + '</div>');
} else {
return false;
}
});
$('.cm-cp-title, .cm-cp-value').wrapAll("<div class='cm-cp-container'/>");
// alignment to middle
$('.cm-coupon').on('resize',function() {
$(".cm-cp-container").css('margin-top', function() {
return($('.cm-coupon').height() - $(this).height()) / 2
});
}).resize();
});//end
.cm-coupon {
width: 340px;
height: 156px;
float: left;color: #fff;
margin: 0 10px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="cm-coupon" data-type="c1" data-value="50"></div>
<div class="cm-coupon" data-type="c2" data-value="20"></div>
<div class="cm-coupon" data-type="c3" data-value="70"></div>

Working Snippet :
$(function() {
'use strict';
var coupon = $('div.cm-coupon');
var colors = new Map([["c1", "black"], ["c2", "green"], ["c3", "blue"]]);
// Settings
coupon.each(function() {
var _coupon = $(this);
var cpValue = _coupon.attr("data-value") + "";
var color = colors.get(_coupon.data('type'));
_coupon.addClass(color).css({
"background" : color,
"display": "table"
});
_coupon.append('<div class="cm-cp-title">' + color + ' here' + '</div>' + '\n' + '<div class="cm-cp-value">' + cpValue + '</div>');
$(_coupon.children()).wrapAll("<div class='cm-cp-container'/>");
});
// alignment to middle
$('.cm-coupon').on('resize',function() {
$(".cm-cp-container").css('margin-top', function() {
return($('.cm-coupon').height() - $(this).height()) / 2
});
}).resize();
});//end
.cm-coupon {
width: 340px;
height: 156px;
float: left;
color: #fff;
margin: 0 10px;
text-align: center;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="cm-coupon" data-type="c1" data-value="50"></div>
<div class="cm-coupon" data-type="c2" data-value="20"></div>
<div class="cm-coupon" data-type="c3" data-value="70"></div>
Explanation :
First
I reduced the code removing the if statements because the only difference between the blocks if/else/else was the color ("black"/"green"/"blue"). I used a Map instead, to switch the value of the color according to the type.
What I did:
var colors = new Map([["c1", "black"], ["c2", "green"], ["c3", "blue"]]);
coupon.each(function () {
var _coupon = $(this);
var color = colors.get(_coupon.data('type'));
And then use color where need to.
Second
The problem you are encoutering is because you are not wrapping all the divs into the container, but wrapping the children of the divs.
So
$('.cm-cp-title, .cm-cp-value').wrapAll("<div class='cm-cp-container'/>");
becomes
$(coupon).wrapAll("<div class='cm-cp-container'/>");
EDIT :
It seems like you want to wrap the inner elements of the coupons instead.
Then use _coupon.children() instead, like this
$(_coupon.children()).wrapAll("<div class='cm-cp-container'/>");
and move it inside the each loop.
I edited the snippet. you can check.
In fact, the way you did it in your code, it is selecting all the matching elements in the document and wrapping it altogether. That is why the last two were moving inside the black div.