Inserting HTML elements with JavaScript

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]);

Answers:

Answer

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...

Answer

You want this

document.body.insertAdjacentHTML( 'afterbegin', '<div id="myID">...</div>' );
Answer

Have a look at insertAdjacentHTML

var element = document.getElementById("one");
var newElement = '<div id="two">two</div>'
element.insertAdjacentHTML( 'afterend', newElement )
// new DOM structure: <div id="one">one</div><div id="two">two</div>

position is the position relative to the element you are inserting adjacent to:

'beforebegin' Before the element itself

'afterbegin' Just inside the element, before its first child

'beforeend' Just inside the element, after its last child

'afterend' After the element itself

Answer

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>');
Answer

To my knowledge, which, to be fair, is fairly new and limited, the only potential issue with this technique is the fact that you are prevented from dynamically creating some table elements.

I use a form to templating by adding "template" elements to a hidden DIV and then using cloneNode(true) to create a clone and appending it as required. Bear in ind that you do need to ensure you re-assign id's as required to prevent duplication.

Answer

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

Answer

If you want to insert HTML code inside existing page's tag use Jnerator. This tool was created specially for this goal.

Instead of writing next code

    var htmlCode = '<ul class=\'menu-countries\'><li
        class=\'item\'><img src=\'au.png\'></img><span>Australia </span></li><li
        class=\'item\'><img src=\'br.png\'> </img><span>Brazil</span></li><li
        class=\'item\'> <img src=\'ca.png\'></img><span>Canada</span></li></ul>';
    var element = document.getElementById('myTag');
    element.innerHTML = htmlCode;

You can write more understandable structure

    var jtag = $j.ul({
        class: 'menu-countries',
        child: [
            $j.li({ class: 'item', child: [
                $j.img({ src: 'au.png' }),
                $j.span({ child: 'Australia' })
            ]}),
            $j.li({ class: 'item', child: [
                $j.img({ src: 'br.png' }),
                $j.span({ child: 'Brazil' })
            ]}),
            $j.li({ class: 'item', child: [
                $j.img({ src: 'ca.png' }),
                $j.span({ child: 'Canada' })
            ]})
        ]
    });
    var htmlCode = jtag.html();
    var element = document.getElementById('myTag');
    element.innerHTML = htmlCode;

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