how to isolate js script from the html code? - javascript

i'd like to isolate the javascript code from the html code in two diferent files, originally I had this code:
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<p id="body">HTML Text</p>
</body>
</html>
<script>
$(document).ready(function () {
$("#body").text("JS Text");
});
</script>
and the output of the <-p-> was the expected "JS Text".
Then I tried to isolate the js script to another file (script.js):
window.onload = function(){
var text = document.getElementById('body');
text.innerHTML ='JS Text';
}
I've also make the reference at the html file:
<script type="text/javascript"src="scripts.js"></script>
but then the output text is no longer the expected (JS Text) but (HTML text)
what else do I need to make the js script work again?

First, it is invalid to place anything after the closing HTML tag, so while your first bit of code worked, it was invalid.
If you remove the JavaScript and place it in its own file, it will continue to work as long as you reference the file properly (use a relative reference and test the file on a web server) and place the script element just prior to the closing body tag so that when the script is processed and attempts to find the right DOM element, the DOM will have been loaded at that time.
FYI:
If you have JQuery in the referenced script file, then your
script that references JQuery will need to occur in the HTML prior
to the script that uses it.
The type attribute in the script tag has not been needed in
several years.
It's not a good idea to name anything body so that you won't cause
confusion with the body element.
Don't use .innerHTML when the string you are working with doesn't
contain any HTML. .innerHTML has security and performance
implications. Use .textContent instead.
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<p id="body">HTML Text</p>
<script src="relativePathToFile.js"></script>
</body>
</html>

Related

D3.js - Add elements in HTML - <script></script> location

I was working with the following tutorial of D3.js: https://www.tutorialspoint.com/d3js/index.htm.
My issue is as follows:
I'm aware of that the location inside the HTML is at the end of the . I mean, I usually put it here:
<body>
<!-- HTML code -->
<script>
<!-- JS code or external JS link -->
</script>
</body>
With this practice, what I'm looking is to run JS after the HTML content renders.
But! When I follow this practice using D3.js, what I discover is that D3.js renders what I add (using d3("html").append(something to append), after the script tags.
For example!
<!DOCTYPE html>
<head>
<title>D3.js Test</title>
</head>
<body>
<div class="div_test">
<h1>I want the D3.js content after this div (but not inside the div)</h1>
</div>
<script type = "text/javascript" src = "https://d3js.org/d3.v4.min.js"></script>
<script>
d3.select("html").append("p").text("I get this text after the script tags");
</script>
</body>
</html>
I'm getting the content as follows:
<!DOCTYPE html>
<html>
<head>
<title>D3.js Test</title>
</head>
<body>
<div class="div_test">
<h1>I want the D3.js content after this div (but not inside the div)</h1>
</div>
<script type="text/javascript" src="https://d3js.org/d3.v4.min.js"></script>
<script>
d3.select("html").append("p").text("I get this text after the script tags");
</script>`
</body><p>I get this text after the script tags</p></html>
Questions!
Is the position of the tag correct?
Is there a possibility to keep the flow without adding a to anchor the expected new tag?
Thanks!!!
You can use selection.insert() to insert an element instead of appending it to the DOM. The second argument to that method determines where the newly created element is put into the DOM tree. If you just want to put it in front of the first <script> element you can do something like:
d3.select("body").insert("p", "script") // <-- insert before first <script>
If you need to place it after the <div>, no matter what the next element might look like, you can use the adjacent sibling combinator to select the sibling element directly following the <div> like so:
d3.select("body").insert("p", "div + *") // <-- insert before next element following div

I need help understanding event handlers and functions in JavaScript?

I wrote HTML document and linked to my JS document.
when I execute the HTML file on my browser it only shows the "Click me!" button, but what I expected it to do was to show the result of my math function when clicked. But .. nothing happens. I'm very new to JavaScript so I'm sure this is a simple answer, but Googling isn't helping ... I appreciate any insight to what I'm doing wrong here.
Here's the code from HTML file:
<!DOCTYPE html>
<html lang=""en">
<head>
<meta charset="UTF-8">
<script src="JS/main.js"></script>
</head>
<body>
<p id="Math">
<button onclick="myFunction()">Click me!</button>
</p>
</body>
</html>
Here's the JS file:
function myFunction(a, b) {return a * b;}
document.getElementById("Math") .innerHTML = myFunction(13, 4);
Not sure what are you trying to do, but if you want to change the content of the "Math" element, you must call the function with parameters (eg: onclick="myFunction(1,3)") and that function should replace the content:
function myFunction(a, b) {
document.getElementById("Math").innerHTML = a * b;
}
<p id="Math">
<button onclick="myFunction(3,4)">Click me!</button>
</p>
Also if you want to preserve the button after clicking, this should be located outside the "Math" element to avoid being removed when replacing innerHTML
You’re including you script file in the header, so it runs before the dom is available. When it executes, it won’t be able to find your id, so nothing will happen. You likely will see an error in the console that your document.getElementById call is returning undefined. Either include it at the end of the body, or add a defer tag:
<script src="JS/main.js" defer></script>
Also, as soon as the code runs, it overwrites the content of the p tag, including the button. Make the p and the button siblings.
One error in your html appears to be caused by an extra " in your lang attribute for your opening html tag. Try deleting it.
<html lang="en">

How to run a script inside the <title></title> tag of a HTML page?

I have a weird situation where I need to run a script inside of the <title></title> tags. I have no access to any of the others parts of the page, including the <head></head> tags. It has to be within the <title></title> tags (the reason is because we are dealing with an iframe response from a 3rd party server and we don't really have access to the full page.).
What I tried was:
<title>
<script type="javascript">
runMyFunction();
</script>
</title>
The problem is that it interprets the whole thing as a script. Is there anything I could do to tell the browser to run that code as a script and not treat it as a string?
You can't.
Per the HTML5 specification, the only permissible content of the <title> tag is plain text. Other tags, such as <script> tags, cannot be present in the context of a <title>.
<title>[trick</title>
<script type="javascript">
runMyFunction();
</script>
<title>:)]</title>
Everyting between the [] is what you should set as title. Most probably it won't work though, 'cause if I were them I would properly encode whatever string you send, in order not to let you do any tricks...
Can you just rewrite <title> later?
<head>
<title>My Title</title>
<script>
document.title = runMyFunction()
</script>
</head>

How to replace custom HTML tag with another tag, using the same content?

Is it possible to create your own text contents (text between the HTML tags) of my custom HTML tags?
I used this code:
<!DOCTYPE html>
<html>
<head>
<script src="https://code.jquery.com/jquery-2.1.4.js"></script>
<script>
$(document).ready(function () {
$("eg").replaceWith("<h2>Put the text content of eg here</h2>");
});
</script>
</head>
<body>
<eg>My text</eg>
</body>
</html>
Between the <h2> tags (don’t think I should only use <h2> tags without JS) in my JavaScript code, any text can be placed that I like to have.
Example: <eg>I can type any text here but it’ll be still in h2 tag settings</eg>.
What should I write between <eg></eg> in JS to have any <h2> text content that will be written in my HTML code?
If you want to replace the <eg>Test</eg> with <h2>Test</h2> then you can just do this: $("eg").replaceWith("<h2>" + $("eg").html() + "</h2>");.
Here is an example: http://plnkr.co/edit/urd69pJSXQngGIsYYSjq
If I'm understanding correctly, you just want to append an element to the DOM, so you can just use the html method as follows:
$("eg").html("<h2>Any text can be placed here</h2>");
Have a look at the docs if you need more info.
Note: You closed but didn't open your body tag.
Replace:
</body>
With something like:
<body> <eg> Your custom content is between body tags now </eg> </body>
And you also have two HTML tags, remove the second
<html>
No. It wouldn't be HTML anymore.
However, if you wrote xHTML (which is a form of XML), then you could extend the DOM with your own elements. But that would be XML, not HTML.
And if you tried adding custom elements to a page, browsers wouldn't know what to do with them. Even if some browsers might display them, it's a very bad idea. Use a class name instead.
Creating and using custom tags is a bad idea. It should be avoided.
You are probably looking for this:
<!DOCTYPE html>
<html>
<head>
<script src="https://code.jquery.com/jquery-2.1.4.js"></script>
<script>
$(document).ready(function () {
$("#my_h2").html("<h2>Any text can be placed here</h2>");
});
</script>
</head>
<h2 id="my_h2"></h2>
</body>
</html>
For more, read-up on CSS selectors. (They are the same as jQuery selectors.)
Hope this helps.

Simple jQuery .load Example Not Working

I'm sure this is a fairly basic question, but I'm relatively new to jQuery so was hoping someone might be able to help.
Basically, I need to load an HTML snippet into a page. This works fine when the snippet contains just HTML, but not when it contains a script.
I've stripped down my code to the bare minimum for clarity. This is index.html:
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.1/jquery.min.js"></script>
</head>
<body>
<h1>Heading</h1>
<div id="banner"></div>
<script>
$(document).ready(function(){
$('#banner').load('banner.html');
});
</script>
</body>
</html>
And banner.html contains just the following (as an example):
<h2>Subheading</h2>
<script>
document.write('Hello');
</script>
The script is executed, but for some reason it strips out the rest of the HTML in both index.html and banner.html (i.e. it just displays "Hello" and nothing else).
Any help greatly appreciated!
document.write after the page has load writes to the document, and at the same overwrites everything else currently in the document, that's why you end up with only the string "hello".
Just remove the document write :
<h2>Subheading</h2>
<p id="test"></p>
<script>
document.getElementById('test').innerHTML = 'hello';
</script>
that is becuase when banner.html is loaded .. the script inside banner.html get executed, which writes "hello" in your document(the document here is your entire index.html)
one way to understand this is by replacing certain content of banner.html rather than the whole document.
banner.html
<h2>Subheading</h2>
<div id="divID"></div>
<script>
$('#divID').html('hello'); //using jquery .. gets the element with id as divID and replace the HTML
</script>
here i am replacing just the div whose id is "divID" rather than replacing the enrite document

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