Inserting HTML elements with JavaScript

Jeremy_Rudd_41021 0
Viewed 209300

Instead of tediously search for workarounds for each type of attribute and event when using the following syntax:

elem = document.createElement("div");
elem.id = 'myID';
elem.innerHTML = ' my Text '
document.body.insertBefore(elem,document.body.childNodes[0]);

Is there a way where I can just declare the entire HTML element as a string? like:

elem = document.createElement("<div id='myID'> my Text </div>");
document.body.insertBefore(elem,document.body.childNodes[0]);
html javascript
7 Answers

Instead of directly messing with innerHTML it might be better to create a fragment and then insert that:

function create(htmlStr) {
    var frag = document.createDocumentFragment(),
        temp = document.createElement('div');
    temp.innerHTML = htmlStr;
    while (temp.firstChild) {
        frag.appendChild(temp.firstChild);
    }
    return frag;
}

var fragment = create('<div>Hello!</div><p>...</p>');
// You can use native DOM methods to insert the fragment:
document.body.insertBefore(fragment, document.body.childNodes[0]);

Benefits:

  1. You can use native DOM methods for insertion such as insertBefore, appendChild etc.
  2. You have access to the actual DOM nodes before they're inserted; you can access the fragment's childNodes object.
  3. Using document fragments is very quick; faster than creating elements outside of the DOM and in certain situations faster than innerHTML.

Even though innerHTML is used within the function, it's all happening outside of the DOM so it's much faster than you'd think...

JimmyP_216770

In old school JavaScript, you could do this:

document.body.innerHTML = '<p id="foo">Some HTML</p>' + document.body.innerHTML;

In response to your comment:

[...] I was interested in declaring the source of a new element's attributes and events, not the innerHTML of an element.

You need to inject the new HTML into the DOM, though; that's why innerHTML is used in the old school JavaScript example. The innerHTML of the BODY element is prepended with the new HTML. We're not really touching the existing HTML inside the BODY.

I'll rewrite the abovementioned example to clarify this:

var newElement = '<p id="foo">This is some dynamically added HTML. Yay!</p>';
var bodyElement = document.body;
bodyElement.innerHTML = newElement + bodyElement.innerHTML;
// note that += cannot be used here; this would result in 'NaN'

Using a JavaScript framework would make this code much less verbose and improve readability. For example, jQuery allows you to do the following:

$('body').prepend('<p id="foo">Some HTML</p>');
user_966560

As others said the convenient jQuery prepend functionality can be emulated:

var html = '<div>Hello prepended</div>';
document.body.innerHTML = html + document.body.innerHTML;

While some say it is better not to "mess" with innerHTML, it is reliable in many use cases, if you know this:

If a <div>, <span>, or <noembed> node has a child text node that includes the characters (&), (<), or (>), innerHTML returns these characters as &amp, &lt and &gt respectively. Use Node.textContent to get a correct copy of these text nodes' contents.

https://developer.mozilla.org/en-US/docs/Web/API/Element/innerHTML

Or:

var html = '<div>Hello prepended</div>';
document.body.insertAdjacentHTML('afterbegin', html)

insertAdjacentHTML is probably a good alternative: https://developer.mozilla.org/en-US/docs/Web/API/Element/insertAdjacentHTML

user_9507040
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