How to pass data from Node.js to html - javascript

I have a simple program and some data strings that I want to pass to HTML page that hosted locally, but I'm getting error: ReferenceError: document is not defined
There's my .js file index.js:
let some_string = "some data";
document.getElementById("dataButton").onclick = function(){
var paragraph = document.createElement("p");
var text = document.createTextNode(some_string);
paragraph.appendChild(text);
var element = document.getElementsByTagName("body")[0];
element.appendChild(paragraph);
}
And there's my HTML test.html:
<!DOCTYPE html>
<html>
<head>
<title>New title</title>
</head>
<body>
<h1>Data page</h1>
<button id="dataButton">Add data</button>
<script src="index.js"></script>
</body>
</html>
Many thanks if someone come up with idea what am I doing wrong!

Update your files to the following
let some_string = "some data";
const dataButton = document.getElementById("dataButton");
dataButton.addEventListener("click", () => {
var paragraph = document.createElement("p");
var text = document.createTextNode(some_string);
paragraph.appendChild(text);
var element = document.getElementsByTagName("body")[0];
element.appendChild(paragraph);
});
<!DOCTYPE html>
<html>
<head>
<title>New title</title>
</head>
<body>
<h1>Data page</h1>
<button id="dataButton">Add data</button>
<script src="./index.js"></script>
</body>
</html>

Related

Cannot read property 'getElementById' of null

I'm writing a simple Cat Clicker app with HTML and JS, but this code keeps spitting 'Cannot read property 'getElementById' of null' error.
What's wrong with it??
<!DOCTYPE html>
<html>
<head>
<title>Cat Clicker</title>
<script>
'use strict'
var cat = document.getElementById("cat");
var counter = document.getElementById("counter");
var meter = 0;
function incClick() {
meter++;
counter.innerHTML = meter;
};
cat.addEventListener('click', incClick);
</script>
</head>
<body>
<p id="counter" >0</p>
<img id="cat" src="img/cat1.jpg" alt="cat">
</body>
</html>
I've corrected a few issues below. You need to use document rather than document.body. You need to ensure the dom has completed loading so I added a content loaded event listener.
<!DOCTYPE html>
<html>
<head>
<title>Cat Clicker</title>
<script>
'use strict'
document.addEventListener("DOMContentLoaded", function() {
var cat = document.getElementById("cat");
var counter = document.getElementById("counter");
var meter = 0;
function incClick() {
meter++;
counter.innerHTML = meter;
};
cat.addEventListener('click', incClick);
});
</script>
</head>
<body>
<p id="counter" >0</p>
<h1 id="cat" src="img/cat1.jpg" alt="cat"></h1>
</body>
</html>
You need to include <script> Tags after the body of the HTML DOC or at least at the very end of your HTML content.
This is b/c how the DOM operates. It loads everything in a sequential order, thus your script it attempting to target an element which doesn't yet exist in the DOM
Just put your script tag after the body tag because I think the problem is that the DOM is rendering after the script runs.
And you can also use document.getElementById instead of document.body.getElementById
just use onclick="incClick()" in your h1 tag , or u can define it as image
<!DOCTYPE html>
<html>
<head>
<title>Cat Clicker</title>
</head>
<body>
<p id="counter">0</p>
<h1 id="cat" src="img/cat1.jpg" alt="cat"></h1>
<p class="counter">0</p>
<img class="cat" src="img/cat2.jpg" alt="cat">
<!--
You need to put the script tag at the end of the body
Because the document must first be created
-->
<script>
'use strict'
var cat = document.getElementById("cat");
var counter = document.getElementById("counter");
var meter = 0;
function incClick() {
meter++;
counter.innerHTML = meter;
};
cat.addEventListener('click', incClick);
</script>
</body>
</html>
This worked for me. You are mistakenly calling getElementById from document.body where it doesn't exist. It is document.getElementById:
<!DOCTYPE html>
<html>
<head>
<title>Cat Clicker</title>
<script>
'use strict'
var cat = document.getElementById("cat");
var counter = document.getElementById("counter");
var meter = 0;
function incClick() {
meter++;
counter.innerHTML = meter;
};
cat.addEventListener('click', incClick);
</script>
</head>
<body>
<p id="counter">0</p>
<h1 id="cat" src="img/cat1.jpg" alt="cat"></h1>
<!-- <p class="counter">0</p>
<img class="cat" src="img/cat2.jpg" alt="cat"> -->
</body>
</html>

How to access parent's JSON object from iframe using javascript

I have a html code like below.
index.html
<html>
<head>
<script>
user_data = {
name: 'xyz',
age: 123
}
</script>
</head>
<body>
.... some code ---
<iframe src="test.html"></iframe>
</body>
</html>
test.html
<html>
<head>
<script>
$(document).ready(function(){
var userName = user_data.name;
});
</head>
<body>
<!--- some other code -->
</body>
</html>
Basically, I am trying to access user_data object which is in index.html from test.html (iframe file).
Can somebody help me to get the value in iframe.
First move your script from head to body.
<html>
<head>
<title>Parcel Sandbox</title>
<meta charset="UTF-8" />
</head>
<body>
<h1>Parent</h1>
<iframe src="./test.html"></iframe>
<script>
user_data = {
name: "xyz",
age: 123
};
</script>
</body>
</html>
Then access parent data with window.parent
<body>
<h1>Test Html</h1>
<div id="app"></div>
<script>
const { parent = {} } = window;
const { user_data = {} } = parent;
const { name, age} = user_data;
const $app = document.getElementById('app')
$app.innerText = `name: ${name}, age: ${age}`
</script>
</body>
Here is a code sample

How do I output a variable from Javascript to html?

I want to inject text into a div using a variable. Here's a Stack Snippet of my code:
tDNA() {
var dna = prompt("Enter the DNA: ");
}
document.getElementById("dna").innerHTML = "DNA: " + dna;
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<src="main.js">
<div id="dna"></div>
</body>
</html>
function promp
You need to import your script like this
<script type="text/javascript" src="main.js"></script>
You can try this out.
HTML
<html>
<head>
</head>
<body>
<script defer src = "main.js"></script>
<div id = "dna">
<p></p>
</div>
</body>
</html>
JavaScript
function promptDNA(){
var dna = prompt("Enter the DNA: ");
d1 = document.querySelector("p");
d1.textContent = dna;
}
promptDNA();
Like this, you have to add the data to the HTML where the variable dna is in scope and then actually call the function
function promptDNA(){
var dna = prompt("Enter the DNA: ");
document.getElementById("dna").textContent = "DNA: " + dna;
}
promptDNA()
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div id="dna"></div>
<script src="main.js"></script>
</body>
</html>
Also, you're importing your script improperly.

JavaScript assistance with code

I wrote these few lines of code and would like the text to change once the button is pressed but its not working. Could you please find out the problem?
var omari = "Omari Lamar";
function omari (){
el = document.getElementById('slice');
el.textContent = omari + "Is a computer Programmer!";
}
<html>
<head>
<title></title>
</head>
<body>
<h1>Title Example</h1>
<button onclick="omari();">Click me</button>
<div id="slice">
sample text
</div>
<script src="app.js"></script>
</body>
</html>
Change the code to:
var omariName ="Omari Lamar";
function omari (){
el = document.getElementById('slice');
el.textContent = omariName + "Is a computer Programmer!";
}
Here you go, Your function name and variable name were the same
var omary ="Omari Lamar";
var omari = function(){
var el = document.getElementById('slice');
el.innerHTML = omary + "Is a computer Programmer!";
};
<html>
<head>
<title>
</title>
<script src="app.js"></script>
</head>
<body>
<h1>Title Example</h1>
<button onclick="omari();">Click me</button>
<div id="slice">
sample text
</div>
<script src="app.js"></script>
</body>
</html>
this is the problem:
you have a variable named omari and a function name omari. so, when you try calling the function omari, javascript actually looks at the variable definition, and not the function. just give them different name.
try the code below.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>test</title>
</head>
<body>
<script>
var _omari ="Omari Lamar";
function omari(){
el = document.getElementById('slice');
el.innerHTML = _omari + " Is a computer Programmer!";
}
</script>
<h1>Title Example</h1>
<button onclick="omari();">Click me</button>
<div id="slice">
sample text
</div>
</body>
</html>

Problems with including external JS file to HTML

I've read many tutorials and tried them, but they don't work.
Just for example I wrote this simple code:
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<p id="testElement"> Html text</p>
<script>
var paragraph = document.getElementById("testElement");
paragraph.innerHTML = "Test Message";
</script>
</body>
</html>
I get Test Message text in my page.
Then I put my JS code to an external file: '/js/js.js'
var paragraph = document.getElementById("testElement");
paragraph.innerHTML = "Test Message";
And modify the HTML file to:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="/js/js.js"></script>
</head>
<body>
<p id="testElement"> Html text</p>
</body>
</html>
When I open the HTML file in a browser, I only get Html text. My JS does not work. Please explain what I am doing wrong.
Your problem is that javascript linked in head is executed before the body is loaded, so you can just put the script at the end of the body like this:
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<p id="testElement"> Html text</p>
<script type="text/javascript" src="js/js.js"></script>
</body>
</html>
Check the JavaScript error console.
Your code runs before the document is rendered so the node testElemet doesn't exist.
Either move your script-include down as the last element in the body or wrap your code in a load/ready event.
function on_document_ready(callback) {
if (document.readyState === "complete") {
callback();
} else {
document.addEventListener("DOMContentLoaded", callback);
}
}
on_document_ready(function () {
var paragraph = document.getElementById("testElemet");
paragraph.innerHTML = "Test Message";
});
This should work fine:
var paragraph = document.getElementById("testElement");
paragraph.innerHTML = "Test Message";
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<p id="testElement">Html text</p>
<script type="text/javascript" src="/js/js.js"></script>
</body>
</html>
Please make sure that <script type="text/javascript" src="/js/js.js"></script> is placed just before </body>.
Try this
var doSomething = function()
{
var paragraph = document.getElementById("testElement");
paragraph.innerHTML = "Test Message";
}
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="js.js"></script>
</head>
<body onload = "doSomething();">
<p id="testElement"> Html text</p>
</body>
</html>
Try saving both the files in the same folder.
Make use of your browsers developer console, to determine whether any errors have occurred.
Regarding 'onload', you can have a look at this link.

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