why div location matters in html? - javascript

I've made a toy example (counter) and I wanted to display the output on an html page.
I found that the javascript code only works when div is "declared" before javascript code.
I thought the order of calling the div doesn't matter.
here is the simple code below:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Random Variable 3</title>
</head>
<body>
<!-- div here (before js code) is working -->
<div id="content2display1"; style="text-align: center; font-size: 80px;"></div>
<script>
let x = 0;
function getRandom1() {
x = x + 1
document.getElementById('content2display1').innerHTML = x; // content2display che viene mandato a html
console.log("x: ", x)
// return rv_i;
};
getRandom1();
setInterval("getRandom1();", 1000);
</script>
<!-- div here is not working... -->
<!-- <div id="content2display1"; style="text-align: center; font-size: 80px;"></div> -->
</body>
</html>
Why the code doesn't work when div is after the javscript code?

If you put your script before the div declaration, the div itself doesn't exist yet in the DOM and your "document.getElementById" returns null.
If you want to put your script before, you should wrap your script body into a DOMContentLoaded listener:
document.addEventListener('DOMContentLoaded', () => {
//your script here
});
Doing so, the script waits for the entire DOM to be loaded before to be executed.

Related

How to update text in window using .innerHTML

I am making a very simple page that just counts how many seconds the user has had the tab open. In the console the seconds update, but on the page in the browser, it ain't.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title>Counter</title>
<script type="text/javascript">
window.seconds = document.getElementById('counts');
var count = setInterval('counter()', 1000);
function counter(){
console.log(seconds)
document.getElementById('counts').innerHTML = window.seconds + 1;
}
</script>
<style>
h2 {
text-align:center;
color:#032441;
font-family:monospace;
}
div {
text-align:center;
color:#032441;
font-size:70px;
font-family:monospace;
}
</style>
</head>
<body>
<script>
document.body.style.backgroundColor = "#EBE9BD"
</script>
<h2>
You have been on this page for
</h2>
<div id="counts">
0
</div>
<h2>
seconds.
</h2>
</body>
</html>
What is the problem?
The variable seconds is declared too soon before the element is even rendered, that's why I added the window.onload wrapper to your code.
You need to use innerHTML to change the content of a div element.
Not related, but you can also style the body tag via CSS rule.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title>Counter</title>
<script type="text/javascript">
window.onload = function () {
var seconds = document.getElementById('counts');
var count = setInterval(counter, 1000);
function counter(){
var newCount = Number(seconds.innerHTML) + 1
console.log(newCount);
seconds.innerHTML = newCount;
}
}
</script>
<style>
body {
backgroundColor: "#EBE9BD";
}
h2 {
text-align: center;
color: #032441;
font-family: monospace;
}
div {
text-align: center;
color: #032441;
font-size: 70px;
font-family: monospace;
}
</style>
</head>
<body>
<h2>
You have been on this page for
</h2>
<div id="counts">
0
</div>
<h2>
seconds.
</h2>
</body>
</html>
You could use the following:
<script type="text/javascript">
window.seconds = document.getElementById('counts');
setInterval('counter()', 1000);
function counter(){
console.log(seconds.innerHTML);
window.seconds.innerHTML++;
}
</script>
Bare in mind that 'counts' is not yet defined as soon as the script runs.
To access the "body" of an Element you have to access it via element.innerHTML which in your case would look like window.seconds.innerHTML = window.seconds.innerHTML + 1
EDIT: But that won't fix your problem.
Your script does not detect the <div id="counts"> element, since it has not been loaded yet, you can fix this by moving the script after the div
Since innerHTML returns a string, performing + will attach both strings and your seconds will look like 011111111 So you'll have to parse it to a string via parseInt(window.seconds.innerHTML)
So changing
window.seconds = window.seconds + 1
to
window.seconds.innerHTML = parseInt(window.seconds.innerHTML) + 1;
and moving the script tag at the very bottom, should to the trick

How can I make my div appear with createElement

I am trying to make another div right under the existing div in the HTML
<html>
<head>
<title>
Media Player
</title>
<script src="script.js"></script>
</head>
<script>
makeOscarPlayer(document.getElementById("my-video"))
</script>
<body>
<div class="my-player">
Hello!
</div>
</body>
</html>
function makeOscarPlayer(){
var div = document.createElement("div");
div.innerHTML = `
hello
`
}
can someone explain to me what I am doing wrong? I am a self-taught developer sorry if my code is not perfectly organized still learning
You are calling the makeOscarPlayer() function before you are creating it.
You need to wrap the makeOscarPlayer() function declaration in a script tag.
You are passing in document.getElementById("my-video") as a parameter to makeOscarPlayer(), but there is no HTML element with an id of 'my-video'. You are giving the function a parameter of null, while the function declaration has no parameters.
You need to tell the script where to put the new element. To do that, you grab an existing element and use parentNode and insertBefore
Here is a barebones version that I got working for your reference:
<html>
<head>
<title>
Media Player
</title>
</head>
<script>
</script>
<body>
<div id="my-player">
Hello!
</div>
</body>
</html>
<script type="text/javascript">
function makeOscarPlayer(){
var div = document.createElement("div");
div.innerHTML = `hello`;
// This grabs the element that you want to create a new element by
var existingDiv = document.getElementById("my-player");
// This tells the script where to put the new element
existingDiv.parentNode.insertBefore( div, existingDiv.nextSibling);
}
// Must be called in the same script block or after the script holding the function declaration is loaded
makeOscarPlayer();
</script>
For more information on how parentNode and insertBefore work, see this Stack Overflow question
You need to append that new element to a specific parent, in your case to my-video.
The function appendChild appends the new element to a parent element.
function makeOscarPlayer(parent) {
var div = document.createElement("div");
div.innerHTML = 'Hello from Ele';
parent.appendChild(div);
}
makeOscarPlayer(document.getElementById("my-video"))
#my-player {
border: 1px dashed green;
padding: 5px;
margin: 5px;
width: 300px;
background-color: #f1f1f1
}
#my-video div {
border: 1px dashed green;
padding: 5px;
margin: 5px;
width: 200px;
font-weight: 700;
}
<div id="my-player">
Hello!
<div id="my-video">
</div>
</div>
It's a good start, but you're calling the function incorrectly and your function isn't adding anything to the page.
we use appendChild to add a node to the page.
In your function you create and add text to a div, but you don't return the node you made(and also you didn't close your line of code with a semi-colon so I added that too) but this should work:
<html>
<head>
<title>
Media Player
</title>
</head>
<body>
<div class="my-player">
Hello!
</div>
<script>
function makeOscarPlayer() {
var div = document.createElement("div");
div.innerHTML = `hello`;
return div;
}
document.getElementById("my-video").appendChild(makeOscarPlayer())
</script>
</body>
</html>
function makeOscarPlayer() {
var div = document.createElement("div");
div.innerHTML = `hello`;
return div;
}
document.getElementById("my-video").appendChild(makeOscarPlayer())
<html>
<head>
<title>
Media Player
</title>
</head>
<body>
<!-- added my-video div -->
<div id="my-video"></div>
<div class="my-player">
Hello!
</div>
</body>
</html>

Position of script tag in html

I am trying to duplicate Expanding Text Areas Made Elegant
Basically it explains how we can achieve something like fb comment box, where its size increases as text files the textarea.
I have this in my index.html:
<html>
<head>
<link rel="stylesheet" type="text/css" href="test.css">
<script src="test.js"></script>
</head>
<body>
<figure>
<div class="expandingArea">
<pre><span></span><br></pre>
<textarea></textarea>
</div>
</figure>
</body>
</html>
And my test.js looks like:
This doesn't really works.
However if I move everything inside the js file to a script tag inside body then it works fine. So my index file would look like:
<html>
<head>
<link rel="stylesheet" type="text/css" href="test.css">
</head>
<body>
<figure>
<div class="expandingArea">
<pre><span></span><br></pre>
<textarea></textarea>
</div>
</figure>
<script>
function makeExpandingArea(container) {
var area = container.querySelector('textarea');
var span = container.querySelector('span');
if (area.addEventListener) {
area.addEventListener('input', function() {
span.textContent = area.value;
}, false);
span.textContent = area.value;
} else if (area.attachEvent) {
// IE8 compatibility
area.attachEvent('onpropertychange', function() {
span.innerText = area.value;
});
span.innerText = area.value;
}
// Enable extra CSS
container.className += ' active';
}var areas = document.querySelectorAll('.expandingArea');
var l = areas.length;while (l--) {
makeExpandingArea(areas[l]);
}
</script>
</body>
</html>
You're not actually using onload
Your formatting is so messed up it's hard to tell, but your init code is in a while loop at the bottom after your onload function.
When you include it in the <head> it runs before any elements exist. That's why the position of it matters.
In your browser(I recommend Chrome for testing) open up the developer tools(via right click and selecting inspect element) and make sure your test.js file's path is correct. Do this by selecting the 'Sources' tab on the top of the developer tools window and then selecting the test.js file on the list of sources.
I also consider it best practice to load your js files at the bottom of your web documents(before the last body tag) to guarantee they load AFTER your dom elements load.
try this in your code:
I have used inside a table andapply a css class "form-control". The properties of this text areas are in side tag in side
html code:
<html>
<body>
<table>
<tr>
<td>Description:</td>
<td><textarea name="DESCRIPTION" id="DESCRIPTION" class="form-control"></textarea></td>
<td></td>
</tr>
</table>
//css-code required inside html:
<style>
textarea.form-control {
height: auto;
resize: none;
width: 300px;
}
</style>
</body>
</html>

Cannot change styles dynamically in CFLayoutArea

I have been writing ColdFusion/JS for 15 years, and this has me totally baffled!
I can run javascript to do anything inside my CFLayoutArea, but it will not let me display or change the styles in JS.
When you load the dashboard.cfm page in the layoutarea, it gives an javascript error anytime you try to change or reference (display) any style attribute related to the div element.
Here is the calling page:
function dashBoard() {
ColdFusion.navigate('dashboard.cfm','content');
}
<cflayout>
<cflayoutarea>
<cfdiv id="content" />
</cflayoutarea>
</cflayout>
Here is dashboard.cfm:
<html>
<head>
<style>
#szliderbar1{
width:37%;
}
</style>
<script>
displayProgress = function() {
var tttt = document.getElementById('szliderbar1');
alert(tttt.style.width);
}
</script>
</head>
<body>
<div id="szliderbar1"> hey
</div>
</body>
</html>
<cfset ajaxonload("displayProgress")>

Trouble with Ace code editor

I have successfully created an Ace editor before, but recently I am making a website called CodeProjects, and I want to put an Ace editor in. Whenever I try, it only shows the text function foo(items) {
var x = "All this is syntax highlighted";
return x;
}. On the page http://ace.c9.io/#nav=embedding&api=ace, it says you only need the code:
<!DOCTYPE html>
<html lang="en">
<head>
<title>ACE in Action</title>
<style type="text/css" media="screen">
#editor {
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
}
</style>
</head>
<body>
<div id="editor">function foo(items) {
var x = "All this is syntax highlighted";
return x;
}
</div>
<script src="/ace-builds/src-noconflict/ace.js" type="text/javascript" charset="utf-8"></script>
<script>
var editor = ace.edit("editor");
editor.setTheme("ace/theme/monokai");
editor.getSession().setMode("ace/mode/javascript");
</script>
</body>
but when I try to embed it (or even just make the editor, not the site), again, it only shows function foo(items) { var x = "All this is syntax highlighted"; return x; }
Any suggestions?
it also says to copy files into your project. If you don't want to do that, include script from cdn
<script src="//cdn.jsdelivr.net/ace/1.1.01/min/ace.js"
type="text/javascript" charset="utf-8"></script>
see http://jsbin.com/ojijeb/165/edit
You need to put the content outside of the editor div [or fetch the content on page load using AJAX]. Either way, you then load the content into the editor with JavaScript: editor.setValue("hello world");.
To set the height of the editor, you resize the div it lives in, then call the editor's resize method.
var div = document.getElementById('editor');
div.style.height = some_multiple_of_the_line_height_for_tidiness;
editor.resize();
In my experience, you need to change div to pre. Just using pre instead of div in following way should solve your problem.
<pre id="editor" >
</pre>

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