Hello I'm new to javascript, and I'm try to write out some code for a test site and I'm having some problems, dow below is my code and I keep getting this error and i can't figure out why.
TypeError: null is not an object (evaluating 'document.getElementById("h3").innerHTML = "<h3>You Are up to date!</h3>"')
This is my second method i tried using. what I'm trying to do it have a have a version list this first one i had was that it would pull a .js file and build a table, but that didn't work so i thought i would try this, but guess what happened? not working
my code that I'm using now is below. if you can help that would be amazing.
thanks, Dakmessier
var current = "1.0";
function get_latest(){
document.getElementById("bob").innerHTML = current;
}
if (local != current){
document.getElementById("Get").innerHTML = "<button>Get the Latest Update!</button>";
} else if (local == current){
document.getElementById("h3").innerHTML = "<h3>You Are up to date!</h3>";
} else {
document.getElementById("h3").innerHTML = "<h3>Sorry, unable to check for update.</h3>";
}
document.getElementById(id) finds an element with a given id value in your HTML. An id value looks like this:
<div id="myHeader">Some Content</div>
And, then you can find that element with:
document.getElementById("myHeader");
ID values must be unique in each document so there should only ever be one element with a given ID.
If an id isn't what you really want, you can find elements other ways, by tag type, by class name, by attribute, etc... using CSS selectors with document.querySelectorAll().
For example, if you wanted to find all <h3> tags, you could do this:
var items = document.querySelectorAll("h3");
Here are some other reasons that document.getElementById(...) might fail to find what you want it to find:
The Javascript code is running before the DOM elements have been parsed and loaded so thus the element is actually not there yet when you're running the code. This is common with code run from the <head> section of the document.
You have an HTML error in how you are specifying the id value in the HTML.
You have an HTML error that causes the browser not to parse your HTML properly.
You have a script error that cause your script to abort before it gets to the part you want to run.
Indeed document.getElementById returns null if it can't find an element with the Id specified.
Also the statement:
if (local != current){
// ..
} else if (local == current){
// ..
} else {
// ..
}
is a bit odd. If local != current is false then local == current must be true. The else if (...) is redundant and the else part will never be run.
hey man the bast thing you should do is the following example, feel free to copy it on your snippet of code:
function myFunction() {
document.getElementById("demo").innerHTML = "Paragraph changed!";
}
<!DOCTYPE html>
<html>
<body>
<p id="demo" onclick="myFunction()">Click me to change my HTML content (innerHTML).</p>
</body>
</html>
I WILL EXPLAIN YOU THIS ANSWER: this is an html + an inline script that makes the inner html work. As far as concerned with your answer it was unclear where your code stopped, anyway test my snippet of code and let me know
I know it's an old question, but I was having the same issue and was trying hard to find the solution for some time.
The problem was that I was executing the script before the page loaded. Thus it wasn't able to find the object that we're trying to catch.
So either use jquery document.ready function or else move your script to the end of the html.
I hope this helps
fix an error of getting the value of a as null
Uncaught TypeError: a is null
code:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<script>
let a = document.getElementById('i');
document.addEventListener('mouseup',function(){
a.innerHTML='clean';
})
</script>
<body>
<h3 id="i">not clean</h3>
</body>
</html>
this shows as error in console as
Uncaught TypeError: a is null
you can fix it by making your script tag before
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<h3 id="i">not clean</h3>
<script>
let a = document.getElementById('i');
document.addEventListener('mouseup',function(){
a.innerHTML='clean';
})
</script>
</body>
</html>
this might fix!!
Related
Hello I'm very new to javascript and doing my first steps I was wondering if I could style the content of a variable in the document.write instruction and I came to this.
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.style1{
background-color: chartreuse;
}
</style>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
var name1;
name1=prompt("Write your name");
document.write('<p class="style1">'+name1+'</p>');
</script>
</body>
</html>
I got that solved by reviewing some posts here the question is how does this actually work?
document.write('<p class="style1">'+name1+'</p>');
I'm not sure I understand why I need to put ' for this instruction could somebody explain that please thank you btw I'm sorry this is a very basic question but I would like to know also if you guys have some more ways to style a document.write it would be nice to know .
I'd suggest taking a slightly different approach. You can add a div to your HTML with an ID of "test" (or whatever you'd like), then edit the innerHTML of that div like so:
document.getElementById("test").innerHTML = name1;
document.write : Write HTML elements with text directly to the HTML document
var name1;
name1=prompt("Write your name");
document.write('<p class="style1">'+name1+'</p>');
Create a variable named name1
Give a value to name1 variable from user input in prompt alert
Write p element with class style1 and its content is value from name1 to HTML document
document.write(); is writing a text in your HTML File.
so if you write like this:
<script>document.write("<p>blah</p>");</script>
then you are writing html Source like <p>blah</p>.
I am a complete beginner to javascript. I am also new to this website. I am asking for help to complete an assignment. I have been trying for more than 4 hours by looking at lecture material and online for a solution. It is causing me a lot of unnecessary stress. Before javascript we only used CSS and Html. I was given 6 javascript tasks to manipulate the html file (taskc.html) already given to me.
The tasks are as follows
Make a statement to change contents of h1 from "Welcome" to "Text"
2nd statement should make an new alert window when the page loads that delivers a message explaining what the page is about
3rd statement should change the title to "text"
4th statement should log the contents (innerHTML) of the first paragraph element in the console.
5th statement should hide the contents of the second paragraph when the page loads
6th statement should change the contents of the header to have a new colour of your choice
Here is that html.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Task C - The Document Object Mode</title>
</head>
<body>
<h1 id="header">Welcome</h1>
<p id="first">This site uses JavaScript</p>
<p id="second">Javascript is very useful</p>
</body>
</html>
Because the actual coding im meant to add is meant to be in the .js file I was given. so I figured I had to link the js file in the html file so I added
<script type="text/javascript" src="taskc.js"></script>
With that out of the way I went to the lecture notes and I thought I would simply need to modify some of the code given to me there like
document.getElementById('demo').innerHTML = 'Hello World!';
When I put this code in brackets I got the error (document is not defined)
I modified it to match the requirements for task 1
here it is
document.getElementById('header').innerHTML = 'text';
I was confused because I didn't know what this error meant and of course Errors and how to fix them are never explained so I had to lookup how to resolve the error.
I found that to fix it I have to declare it as a variable so I ended up doing this.
var document = 'taskc.html';
When I did this for document, alert and console all the errors went away, but when I did a live preview only statement 1 was working
If anyone could help me fix this I would really appreciate because I don't understand enough javascript to be able to complete this in a reasonable amount of time.
So first: Please use Javascript functions to keep your code tidy and clean.
Example:
HTML:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Task C - The Document Object Mode</title>
</head>
<body>
<h1 id="header">Welcome</h1>
<p id="first">This site uses JavaScript</p>
<p id="second">Javascript is very useful</p>
<script type="text/javascript" src="taskc.js">test();</script>
</body>
</html>
function test(){
alert("This is a test!");
}
Always implement scripts that are document referenced at the bottom of your html.
If you use JQuery you can use following code to check document is loaded:
$(document).ready(function(){
//foo bar
});
I'm looking for a Javascript equivalent of a technique I've been using in PHP. That is, to place even the most basic page setup:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
...in a php file like 'doc_start.php' and then start every page in my site with...
<?php require_once('/path/to/doc_start.php); ?>
Now I need to begin a project that's strictly HTML and JS (no PHP) and want a similar way to avoid duplicating basic, common HTML elements. Obviously, I want to do more than this very basic stuff, like import JQuery in every page, link to a common stylesheet, etc. Again, all easy in PHP, but I'm still kind of a newbie in JS.
I've read about HTML5 includes, but can't seem to find anything that addresses what I want to do
In order to import other pages into your current document, you need to use a link tag.
For example....
<head>
<link rel="import" href="/path/to/imports/stuff.html">
</head>
This will allow you to reference other html, css or javascript documents into your page without copying and pasting the same code within each page.
https://www.w3schools.com/html/html_links.asp
Javascript and PHP are different languages for very different purposes. But assuming you have some element you don't want to repeat some elements one solution is the following:
Save the HTML elements that you don't want to keep repeating as a string. Then use the .innerHTML property to add elements.
The .innerHTML property stores the mark up of an element as a string.
For example, if we have the following <div>:
<div class="example"> <br> Hello there this is a test! </div>
...and we use .innerHTML:
console.log(document.querySelector(".example").innerHTML);
It will output "<br> Hello there this is a test!".
We can add to the .innerHTML using the += operator. So if you want to add something inside the body it's as simple as:
var something = "some HTML";
document.body.innerHTML += something;
Hope this was what you were looking for!
I am working on an app using node_webkit combining HTML, CSS and JS. In one part of my app I want to update the Array.prototype so that I can access the last element of an array easily. The code for that is:
if (!Array.prototype.last){
Array.prototype.last = function(){
return this[this.length - 1];
};
}
If I run only the js-file that works fine and as expected. If I include that js-file into an HTML document it seems that the prototype of the array stays unchanged and I get the error:
data.last is not a function
Do I have to change something so that I can run my code normally from an HTML file or does that not work at all and I have to take the long way around and access each array with array[array.length - 1]?
The HTML code I use to include the script is:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="../CSS/Cocktails.css">
<title>Cocktails</title>
<script type="text/javascript" src="../JavaScript/Cocktail.js"></script>
</head>
<body>
/* some elements, that don't use the script yet */
</body>
</html>
It sounds like you're not calling the function, you'd want to call it like data.last() where data is some array that you've declared. Here's a JSFiddle of it in action.
In ES5 you need to use defineProperties in order to modify the Array prototype in an enumberable way:
Following should work,
Object.defineProperties(Array.prototype,
{ last: { value: function() { return this[this.length - 1]; } } });
More information at:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperties
Really getting in to javascript and looking around at some patterns. One I have come accross is the module pattern. Its seems like a nice way to think of chucks of functionality so I went ahead and tried to implement it with jQuery. I ran in to a snag though. Consider the following code
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8">
<title>index</title>
<script type="text/javascript" charset="utf-8" src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script>
<script type="text/javascript" charset="utf-8">
$(document).ready(function(){
var TestClass2 = (function(){
var someDiv;
return {
thisTest: function ()
{
someDiv = document.createElement("div");
$(someDiv).append("#index");
$(someDiv).html("hello");
$(someDiv).addClass("test_class");
}
}
})();
TestClass2.thisTest();
});
</script>
</head>
<body id="index" onload="">
<div id="name">
this is content
</div>
</body>
</html>
The above code alerts the html content of the div and then adds a class. These both use jQuery methods. The problem is that the .html() method works fine however i can not add the class. No errors result and the class does not get added. What is happening here? Why is the class not getting added to the div?
Ah, now that you've updated your question I can better answer your question. You should change the append to appendTo considering you're wanting to move the newly created element inside of the already present #index.
$(document).ready(function() {
var TestClass2 = (function() {
var someDiv = $("#name");
return {
thisTest: function() {
someDiv = document.createElement("div");
$(someDiv)
.html("hello")
.addClass("test_class")
.appendTo("#index");
}
}
})();
TestClass2.thisTest();
});
Hope this helps!
I copied and pasted your code and it works for me.
Make sure you're not simply viewing source to see if the class is applied because doing so simply shows you the HTML that was sent from the server - any DOM updates that occur through JavaScript will not be reflected.
To view the live DOM, use a tool like Firebug or WebKit's Inspector (comes built-in to Safari and Chrome).
Your code works great!
http://jsfiddle.net/lmcculley/p3fDX/