Inserting arbitrary HTML into a DocumentFragment

Question

I know that adding innerHTML to document fragments has been recently discussed, and will hopefully see inclusion in the DOM Standard. But, what is the workaround you're supposed to use in the meantime?

That is, take

var html = '<div>x</div><span>y</span>';
var frag = document.createDocumentFragment();

I want both the div and the span inside of frag, with an easy one-liner.

Bonus points for no loops. jQuery is allowed, but I've already tried $(html).appendTo(frag); frag is still empty afterward.

Solution 1

Here is a way in modern browsers without looping:

var temp = document.createElement('template');
temp.innerHTML = '<div>x</div><span>y</span>';

var frag = temp.content;

or, as a re-usable

function fragmentFromString(strHTML) {
    var temp = document.createElement('template');
    temp.innerHTML = strHTML;
    return temp.content;
}

UPDATE: I found a simpler way to use Pete's main idea, which adds IE11 to the mix:

function fragmentFromString(strHTML) {
    return document.createRange().createContextualFragment(strHTML);
}

The coverage is better than the <template> method and tested ok in IE11, Ch, FF.

Live test/demo available http://pagedemos.com/str2fragment/

Solution 2

Currently, the only way to fill a document fragment using only a string is to create a temporary object, and loop through the children to append them to the fragment.

• Since it's not appended to the document, nothing is rendered, so there's no performance hit.
• You see a loop, but it's only looping through the first childs. Most documents have only a few semi-root elements, so that's not a big deal either.

If you want to create a whole document, use the DOMParser instead. Have a look at this answer.

Code:

var frag = document.createDocumentFragment(),
    tmp = document.createElement('body'), child;
tmp.innerHTML = '<div>x</div><span>y</span>';
while (child = tmp.firstElementChild) {
    frag.appendChild(child);
}

A one-liner (two lines for readability) (input: String html, output: DocumentFragment frag):

var frag =document.createDocumentFragment(), t=document.createElement('body'), c;
t.innerHTML = html; while(c=t.firstElementChild) frag.appendChild(c);

Solution 3

Use Range.createContextualFragment:

var html = '<div>x</div><span>y</span>';
var range = document.createRange();
// or whatever context the fragment is to be evaluated in.
var parseContext = document.body; 
range.selectNodeContents(parseContext);
var fragment = range.createContextualFragment(html);

Note that the primary differences between this approach and the <template> approach are:

• Range.createContextualFragment is a bit more widely supported (IE11 just got it, Safari, Chrome and FF have had it for a while).

• Custom elements within the HTML will be upgraded immediately with the range, but only when cloned into the real doc with template. The template approach is a bit more 'inert', which may be desirable.

Solution 4

No one ever provided the requested "easy one-liner".

Given the variables…

var html = '<div>x</div><span>y</span>';
var frag = document.createDocumentFragment();

… the following line will do the trick (in Firefox 67.0.4):

frag.append(...new DOMParser().parseFromString(html, "text/html").body.childNodes);

Solution 5

@PAEz pointed out that @RobW's approach does not include text between elements. That's because children only grabs Elements, and not Nodes. A more robust approach might be as follows:

var fragment = document.createDocumentFragment(),
    intermediateContainer = document.createElement('div');

intermediateContainer.innerHTML = "Wubba<div>Lubba</div>Dub<span>Dub</span>";

while (intermediateContainer.childNodes.length > 0) {
    fragment.appendChild(intermediateContainer.childNodes[0]);
}

Performance may suffer on larger chunks of HTML, however, it is compatible with many older browsers, and concise.

View more solutions

Comments

[gdoron is supporting Monica]

@RobW. That's not a good reason to down vote if the OP wrote " jQuery is allowed"

[Rob W]

@gdoron The main reason that I downvoted the answer is that the textual explanation is 100% wrong. A DocumentFragment object can have an arbitrary number of child elements. My previous comment was referring to Morgan's comment at Michal's answer.

[Morgan T.]

@RobW it was just a playful comment because we posted at the exact same time. I can see how others would see it as inappropriate though. I've removed it. I see what you mean about my logic too. During my testing I made a mistake and based my explanation off that. I've updated my answer. Thanks

[Domenic]

Yeah, I don't want the extra container element.

[Domenic]

Yeah, same problem as Michal's answer; this does not satisfy the problem statement, since it inserts an extra wrapper div#main.

[Domenic]

Bleh, I guess this is the only way to go. At least you actually answered the question and satisfied the problem statement :). Still, it's annoying to have to loop; ah well.

[Michal]

When you appending you always need an "extra" (or should I say a target) container - be a body or some other tag. If you don't want that it is loops for you

[Domenic]

I guess I was hoping there would be a way to copy all children of holder into frag in one go (without looping). appendChildren or something. But it sounds like no such method exists.

[Christophe]

@Domenic such a method exists...that's the whole point of document fragments ;-) your real issue here is that you're dealing with a html string, not html elements.

[B.F.]

@Domenic frag = holder.cloneNode(true);

[Marcello di Simone]

Not supported by IE at all, so "modern browsers" is a bit misleading.

[PAEz]

Misses text between elements.... var elemQueried = document.createDocumentFragment(); var tmp = document.createElement('body'), child; tmp.innerHTML = '<div>x</div>Bleh<span>y</span>'; var children = tmp.childNodes; while(children.length){ elemQueried.appendChild(children[0]); }

[Jonatas Walker]

Almost upvoted, if it weren't that <font> tag in the demo.

[Munawwar]

An issue with createContextualFragment is that, html like '<td>test</td>' would ignore the td (and only create 'test' text node). template tag solution is the way to go. BTW Edge 13 supports template tag now.

[tomalec]

Do you have any idea for nice Safari alternative? or at least an issue in their tracker?

[Matt]

@PAEz Posted an answer below that takes care of this issue.

[Rob W]

Even conciser: .firstChild - while (intermediateContainer.firstChild) fragement.appendChild(intermediateContainer.firstChild);

[Matt]

Good suggestion. I suppose it's a question of style at this point. Thanks!

[KevBot]

This does not work (at least in Chrome). When using insertAdjacentHTML inside of a DocumentFragment, you will get this error: Uncaught DOMException: Failed to execute 'insertAdjacentHTML' on 'Element': The element has no parent. Also, addChild is not a method, you should be using appendChild

[jcubic]

I've needed array off element nodes from Fragement and this works in Chrome and IE11 [].slice.call(temp.content ? temp.content.children : temp.childNodes)

[jcubic]

Plus for supporting td in IE.

[Johan]

This should be the selected answer and deserves way more upvotes <3

[Victoria]

Careful! not standardized.

[Bharata]

It does not work with td, th elements for table.

[Uchenna Ajah]

No doubt! This is the best answer! Both documentFragments and DOMParser are supported by older browsers, including IE9. Thumbs up