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I am new to Javascript (and programming in general) and have been trying to get a basic grasp on working with the DOM. Apologies if this is a very basic mistake, but I looked around and couldn't find an answer.
I am trying to use the appendChild method to add a heading and some paragraph text into the in the very basic HTML file below.
<html> <head> <title>JS Practice</title> </head> <body> <script src="script.js"></script> <div id = "main"> <h1>Simple HTML Page</h1> <p>This is a very simple HTML page.</p> <p>It's about as basic as they come. It has: </p> <ul> <li>An H1 Tag</li> <li>Two paragraphs</li> <li>An unordered list</li> </ul> </div> <div id="javascript"> </div> </body> </html> Here is the js code:
var newHeading = document.createElement("h1"); var newParagraph = document.createElement("p"); newHeading.innerHTML = "New Heading!"; newParagraph.innerHTML = "Some text for a paragraph."; document.getElementById("javascript").appendChild(newHeading); document.getElementById("javascript").appendChild(newParagraph); Running it causes an error: "Cannot call method 'appendChild' of null"
Help? I can't figure out why this isn't working...
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appendChild() The appendChild() method of the Node interface adds a node to the end of the list of children of a specified parent node. If the given child is a reference to an existing node in the document, appendChild() moves it from its current position to the new position.
The "appendChild is not a function" error occurs for multiple reasons: calling the appendChild() method on a value that is not a DOM element. placing the JS script tag above the code that declares the DOM elements. misspelling appendChild - it's case sensitive.
The "Cannot read property 'appendChild' of null" error occurs when trying to call the appendChild method on a DOM element that doesn't exist. To solve the error, make sure to only call the appendChild method on valid DOM elements.
The removeChild() method removes an element's child.
Assuming this code is inside the script.js file, this is because the javascript is running before the rest of the HTML page has loaded.
When an HTML page loads, when it comes across a linked resource such as a javascript file, it loads that resource, executes all code it can, and then continues running the page. So your code is running before the <div> is loaded on the page.
Move your <script> tag to the bottom of the page and you should no longer have the error. Alternatively, introduce an event such as <body onload="doSomething();"> and then make a doSomething() method in your javascript file which will run those statements.
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There is an easier way to resolve this issue. Put your JavaScript inside of a function and use the window.onload. So for instance:
window.onload = function any_function_name() { var newHeading = document.createElement("h1"); var newParagraph = document.createElement("p"); newHeading.innerHTML = "New Heading!"; newParagraph.innerHTML = "Some text for a paragraph."; document.getElementById("javascript").appendChild(newHeading); document.getElementById("javascript").appendChild(newParagraph); } Now, you do not have to move your tag because that will run your code after the HTML has loaded.
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