innerHTML or DOM

JavaScript performance comparison

Revision 4 of this test case created by Neil Jenkins on 4th January 2012

Info

Most dynamic websites use innerHTML because they think it's faster. But is it? This compares hand-optimised DOM and innerHTML along with a sugared DOM and Handlebars templated version.

Preparation code

<script src="http://cdnjs.cloudflare.com/ajax/libs/handlebars.js/1.0.0.beta2/handlebars.min.js"></script>

<script id="template" type="text/x-handlebars-template"><div class="Foo{{#if isSelected}} selected{{/if}}{{#if isActive}} selected{{/if}}">
    <label><input type="checkbox" checked="{{#if isSelected}}checked{{/if}}"></label>
    <button class="button" title="A title">The button text</button>
    <a href="{{href}}"><span class="lorem{{#ifGreaterThanOne total}} ipsum{{/ifGreaterThanOne}}">
        <span class="dolores" unselectable="on">{{text}}</span>
        {{#ifGreaterThanOne total}}
        <span class="total" unselectable="on">({{total}})</span>
        {{/ifGreaterThanOne}}
        {{#if yes}}
        <span class="yes">*</span>
        {{/if}}
        <span class="text" unselectable="on">
        {{#ifGreaterThanOne total}}{{text}}{{/ifGreaterThanOne}}
        </span>
        <time unselectable="on" title="{{displayDate}}">{{displayDate}}</time>
        <span class="preview" unselectable="on">{{preview}}</span>
    </a>
</div>
</script>

<script type="text/javascript">
"use strict";

var create = (function () {

var doc = document;

var directProperties = {
    'class': 'className',
    className: 'className',
    defaultValue: 'defaultValue',
    'for': 'htmlFor',
    html: 'innerHTML',
    text: 'textContent',
    value: 'value'
};

var booleanProperties = {
    checked: 1,
    defaultChecked: 1,
    disabled: 1,
    multiple: 1,
    selected: 1
};

var setProperty = function ( el, key, value ) {
    var prop = directProperties[ key ];
    if ( prop ) {
        el[ prop ] = ( value == null ? '' : '' + value );
    } else if ( booleanProperties[ key ] ) {
        el[ key ] = !!value;
    } else if ( value == null ) {
        el.removeAttribute( key );
    } else {
        el.setAttribute( key, '' + value );
    }
};

var appendChildren = function ( el, children ) {
    var i, l, node;
    for ( i = 0, l = children.length; i < l; i += 1 ) {
        node = children[i];
        if ( node ) {
            if ( node instanceof Array ) {
                appendChildren( el, node );
            } else {
                if ( typeof node === 'string' ) {
                    node = doc.createTextNode( node );
                }
                el.appendChild( node );
            }
        }
    }
};

var splitter = /(#|\.)/;

var create = function ( tag, props, children ) {
    if ( props instanceof Array ) {
        children = props;
        props = null;
    }
    
    var parts, name, el,
        i, j, l, node, prop;
    
    if ( splitter.test( tag ) ) {
        parts = tag.split( splitter );
        tag = parts[0];
        if ( !props ) { props = {}; }
        for ( i = 1, j = 2, l = parts.length; j < l; i += 2, j += 2 ) {
            name = parts[j];
            if ( parts[i] === '#' ) {
                props.id = name;
            } else {
                props.className = props.className ?
                    props.className + ' ' + name : name;
            }
        }
    }
    
    el = doc.createElement( tag );
    if ( props ) {
        for ( prop in props ) {
            setProperty( el, prop, props[ prop ] );
        }
    }
    if ( children ) {
        appendChildren( el, children );
    }
    return el;
};

return create;

}() );

var data = {
    isSelected: true,
    isActive: false,
    href: 'http://www.google.com',
    total: 4,
    displayDate: '28th December 2011',
    text: 'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.',
    preview: 'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.'
};

var genDOMWithSugar = function ( data ) {
    var el = create;
    return el( 'div', {
        className: 'Foo' +
            ( data.isSelected ? ' selected' : '' ) +
            ( data.isActive ? ' active' : '' )
    }, [
        el( 'label', [
            el( 'input', {
                type: 'checkbox',
                checked: data.isSelected ? 'checked': ''
            })
        ]),
        el( 'button.button', {
            title: 'A title',
            text: 'The button text'
        }),
        el( 'a', {
            href: data.href
        }, [
            el( 'span', {
                className: 'lorem' +
                    ( data.total > 1 ? ' ipsum' : '' )
            }, [
                el( 'span.dolores', {
                    unselectable: 'on'
                }, [
                    data.text
                ]),
                data.total > 1 ? el( 'span.total', {
                    unselectable: 'on',
                    text: '(' + data.total + ')'
                }) : null
            ]),
            data.yes ? el( 'span.yes', {
                text: '*'
            }) : null,
            el( 'span.text', {
                unselectable: 'on'
            }, [
                data.total > 1 ? data.text : null
            ]),
            el( 'time', {
                unselectable: 'on',
                text: data.displayDate,
                title: data.displayDate
            }),
            el( 'span.preview', {
                unselectable: 'on',
                text: data.preview
            })
        ])
    ] );
};

var genDOM = function ( data ) {
    var doc = document,
        div = doc.createElement( 'div' );
    
    div.className = 'Foo' +
        ( data.isSelected ? ' selected' : '' ) +
        ( data.isActive ? ' active' : '' );
    
    var label = doc.createElement( 'label' ),
        input = doc.createElement( 'input' );
    input.setAttribute( 'type', 'checkbox' );
    input.checked = !!data.isSelected;
    label.appendChild( input );
    div.appendChild( label );
    
    var button = doc.createElement( 'button' );
    button.className = 'button';
    button.setAttribute( 'title', 'A title' );
    button.textContent = 'The button text';
    div.appendChild( button );
    
    var a = doc.createElement( 'a' );
    a.setAttribute( 'href', data.href );
    
    var span = doc.createElement( 'span' );
    span.className = 'lorem' +
        ( data.total > 1 ? ' ipsum' : '' );
    
    var span2 = doc.createElement( 'span' );
    span2.className = 'dolores';
    span2.setAttribute( 'unselectable', 'on' );
    span2.appendChild( doc.createTextNode( data.text ) );
    span.appendChild( span2 );
    
    if ( data.total > 1 ) {
        span2 = doc.createElement( 'span' );
        span2.className = 'total';
        span2.setAttribute( 'unselectable', 'on' );
        span2.textContent = '(' + data.total + ')';
        span.appendChild( span2 );
    }
    a.appendChild( span );
    if ( data.yes ) {
        span = doc.createElement( 'span' );
        span.className = 'yes';
        span.textContent = '*';
        a.appendChild( span );
    }
    
    span = doc.createElement( 'span' );
    span.className = 'text';
    span.setAttribute( 'unselectable', 'on' );
    if ( data.total > 1 ) {
        span.appendChild( doc.createTextNode(  data.text ) );
    }
    a.appendChild( span );
    
    var time = doc.createElement( 'time' );
    time.setAttribute( 'unselectable', 'on' );
    time.textContent = data.displayDate;
    time.setAttribute( 'title', data.displayDate );
    a.appendChild( time );
    
    span = doc.createElement( 'span' );
    span.className = 'preview';
    span.setAttribute( 'unselectable', 'on' );
    span.textContent = data.preview;
    a.appendChild( span );
    
    div.appendChild( a );
    
    return div;
};

var genDOMWithInnerHTML = function ( data ) {
    var div = document.createElement( 'div' );
    div.innerHTML = '<div class="Foo' +
            (data.isSelected ? ' selected' : '') +
            (data.isActive ? ' active' : '') + '">' +
        '<label><input type="checkbox" checked="' +
        (data.isSelected ? 'checked': '') + '"></label>' +
        '<button class="button" title="A title">The button text</button>' +
        '<a href="' + data.href + '"><span class="lorem' +
            ( data.total > 1 ? ' ipsum' : '' ) +
            '"><span class="dolores" unselectable="on">' + data.text +
            '</span>' + ( data.total > 1 ?
                '<span class="total" unselectable="on">(' + data.total + ')</span>' :
                '') +
            '</span>' + (data.yes ? '<span class="yes">*</span>' : '') +
            '<span class="text" unselectable="on">' +
            (data.total > 1 ? data.text : null) +
            '</span>' +
            '<time unselectable="on" title="' + data.displayDate + '">' +
            data.displayDate +
            '</time><span class="preview" unselectable="on">' + data.preview +
            '</span></a></div>';
    return div.firstChild;
};

Handlebars.registerHelper( 'ifGreaterThanOne', function( number, options ) {
    if ( number > 1 ) { return options.fn( this ); }
});

var source   = document.getElementById( 'template' ).innerHTML;
var template = Handlebars.compile( source );
var genHandlebarsTemplate = function ( data ) {
    var div = document.createElement( 'div' );
    div.innerHTML = template( data );
    return div.firstChild;
};
</script>

Preparation code output

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test		Ops/sec
innerHTML	`genDOMWithInnerHTML( data );`	pending…
DOM	`genDOM( data );`	pending…
Sugared DOM	`genDOMWithSugar( data );`	pending…
Handlebars	`genHandlebarsTemplate( data );`	pending…

Compare results of other browsers

Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

Revision 7: published on 23rd February 2012
Revision 8: published by Alex Sexton on 23rd February 2012
Revision 9: published on 23rd February 2012
Revision 14: published on 11th July 2012
Revision 15: published by Eamon Nerbonne on 29th November 2012
Revision 16: published on 30th November 2012
Revision 17: published by Eamon Nerbonne on 30th November 2012
Revision 18: published on 30th November 2012

6 comments

Harry Walter commented on 22nd February 2012: ∞

I think this test shows that given a modern browser that is not opera the innerHTML method is always faster…

garry commented on 22nd February 2012: ∞

Harry, you are wrong.

Gunnar Bittersmann commented on 22nd February 2012: ∞

Quite the contrary, for most browsers the blue bar (DOM) is longer than the green bar (innerHTML), i.e. the DOM methods are faster.

(The vertical axis does not show the time, but its reciprocal.)

Will Earp commented on 22nd February 2012: ∞

When serving documents using application/xhtml+xml, you shouldn’t use innerHTML, so this is a thumbs up to moving towards constructing document components in a more structured manner.

toType commented on 23rd February 2012: ∞