Tuesday 2nd September, 2014

Alphabet input search - Part II

Continuing a three part series of posts exploring the DataTables custom search options, API and feature plug-ins, this second post extends the alphabet search control introduced in part I of this series to give quick visual feedback to the end user for search terms. This visual information will indicate how many records are in the table for each search option. This is done through use of the DataTables API and displaying an information element using jQuery.

The alphabet search

Before exploring the code in this post, the following example shows what we will be building here.

Name	Position	Office	Age	Start date	Salary
Tiger Nixon	System Architect	Edinburgh	61	2011-04-25	$320,800
Garrett Winters	Accountant	Tokyo	63	2011-07-25	$170,750
Ashton Cox	Junior Technical Author	San Francisco	66	2009-01-12	$86,000
Cedric Kelly	Senior Javascript Developer	Edinburgh	22	2012-03-29	$433,060
Airi Satou	Accountant	Tokyo	33	2008-11-28	$162,700
Brielle Williamson	Integration Specialist	New York	61	2012-12-02	$372,000
Herrod Chandler	Sales Assistant	San Francisco	59	2012-08-06	$137,500
Rhona Davidson	Integration Specialist	Tokyo	55	2010-10-14	$327,900
Colleen Hurst	Javascript Developer	San Francisco	39	2009-09-15	$205,500
Sonya Frost	Software Engineer	Edinburgh	23	2008-12-13	$103,600
Jena Gaines	Office Manager	London	30	2008-12-19	$90,560
Quinn Flynn	Support Lead	Edinburgh	22	2013-03-03	$342,000
Charde Marshall	Regional Director	San Francisco	36	2008-10-16	$470,600
Haley Kennedy	Senior Marketing Designer	London	43	2012-12-18	$313,500
Tatyana Fitzpatrick	Regional Director	London	19	2010-03-17	$385,750
Michael Silva	Marketing Designer	London	66	2012-11-27	$198,500
Paul Byrd	Chief Financial Officer (CFO)	New York	64	2010-06-09	$725,000
Gloria Little	Systems Administrator	New York	59	2009-04-10	$237,500
Bradley Greer	Software Engineer	London	41	2012-10-13	$132,000
Dai Rios	Personnel Lead	Edinburgh	35	2012-09-26	$217,500
Jenette Caldwell	Development Lead	New York	30	2011-09-03	$345,000
Yuri Berry	Chief Marketing Officer (CMO)	New York	40	2009-06-25	$675,000
Caesar Vance	Pre-Sales Support	New York	21	2011-12-12	$106,450
Doris Wilder	Sales Assistant	Sydney	23	2010-09-20	$85,600
Angelica Ramos	Chief Executive Officer (CEO)	London	47	2009-10-09	$1,200,000
Gavin Joyce	Developer	Edinburgh	42	2010-12-22	$92,575
Jennifer Chang	Regional Director	Singapore	28	2010-11-14	$357,650
Brenden Wagner	Software Engineer	San Francisco	28	2011-06-07	$206,850
Fiona Green	Chief Operating Officer (COO)	San Francisco	48	2010-03-11	$850,000
Shou Itou	Regional Marketing	Tokyo	20	2011-08-14	$163,000
Michelle House	Integration Specialist	Sydney	37	2011-06-02	$95,400
Suki Burks	Developer	London	53	2009-10-22	$114,500
Prescott Bartlett	Technical Author	London	27	2011-05-07	$145,000
Gavin Cortez	Team Leader	San Francisco	22	2008-10-26	$235,500
Martena Mccray	Post-Sales support	Edinburgh	46	2011-03-09	$324,050
Unity Butler	Marketing Designer	San Francisco	47	2009-12-09	$85,675
Howard Hatfield	Office Manager	San Francisco	51	2008-12-16	$164,500
Hope Fuentes	Secretary	San Francisco	41	2010-02-12	$109,850
Vivian Harrell	Financial Controller	San Francisco	62	2009-02-14	$452,500
Timothy Mooney	Office Manager	London	37	2008-12-11	$136,200
Jackson Bradshaw	Director	New York	65	2008-09-26	$645,750
Olivia Liang	Support Engineer	Singapore	64	2011-02-03	$234,500
Bruno Nash	Software Engineer	London	38	2011-05-03	$163,500
Sakura Yamamoto	Support Engineer	Tokyo	37	2009-08-19	$139,575
Thor Walton	Developer	New York	61	2013-08-11	$98,540
Finn Camacho	Support Engineer	San Francisco	47	2009-07-07	$87,500
Serge Baldwin	Data Coordinator	Singapore	64	2012-04-09	$138,575
Zenaida Frank	Software Engineer	New York	63	2010-01-04	$125,250
Zorita Serrano	Software Engineer	San Francisco	56	2012-06-01	$115,000
Jennifer Acosta	Junior Javascript Developer	Edinburgh	43	2013-02-01	$75,650
Cara Stevens	Sales Assistant	New York	46	2011-12-06	$145,600
Hermione Butler	Regional Director	London	47	2011-03-21	$356,250
Lael Greer	Systems Administrator	London	21	2009-02-27	$103,500
Jonas Alexander	Developer	San Francisco	30	2010-07-14	$86,500
Shad Decker	Regional Director	Edinburgh	51	2008-11-13	$183,000
Michael Bruce	Javascript Developer	Singapore	29	2011-06-27	$183,000
Donna Snider	Customer Support	New York	27	2011-01-25	$112,000
Name	Position	Office	Age	Start date	Salary

Mouse control

First consider how we wish to display the additional search information to the end user. As you will be able to see from the example above, a simple box with a number is shown below each letter in the alphabet as the user moves their mouse over the characters. The number indicates how many records are available for that search term (how that number is calculated is discussed below).

This is primarily simple Javascript and jQuery rather than being DataTables specific, so I won't delve into much detail here, but basically what we do is attach the element for the number box (info below) to the alphabet container (alphabet from the code developed in part I). As the mouse enters a search term element (a span tag) the information element is made visible with its content and position being updated to be suitable for the search term. As the mouse is removed, the information element is also removed.

var info = $('<div class="alphabetInfo"></div>')
    .appendTo( alphabet );

alphabet
    .on( 'mouseenter', 'span', function () {
        info
            .css( {
                opacity: 1,
                left: $(this).position().left,
                width: $(this).width()
            } )
            .html( $(this).data('match-count') )
    } )
    .on( 'mouseleave', 'span', function () {
        info.css('opacity', 0);
    } );

Data attributes

In the code above, the search count for each letter is read from the data attribute match-count - for example, you could consider the HTML to look like:

<div class="alphabet">
    <span data-match-count="57">None</span>
    <span data-match-count="3">A</span>
    <span data-match-count="4">B</span>
    <span data-match-count="5">C</span>
    ...
</div>

Our task now is simply to add those data attributes to the alphabet elements as they are created.

To get the data that is available in the first column we can use the DataTables column().data() method. Passing in an index of 0 to the column() method will retrieve the data for the first column, which can than be iterated over to count the number of times each character appears as the first letter in the data set.

For this we can write a simple function to bin the data, producing an object which has a count for each letter (the absence of a letter in the object represents a zero count):


function bin ( data ) {
    var letter, bins = {};

    for ( var i=0, ien=data.length ; i<ien ; i++ ) {
        letter = data[i].charAt(0).toUpperCase();

        if ( bins[letter] ) {
            bins[letter]++;
        }
        else {
            bins[letter] = 1;
        }
    }

    return bins;
}

The resulting object might look like:

{
    "A": 3,
    "B": 4,
    "C": 5,
    ...
}

Finally we call that function with the data from column().data() and then use the binned data when creating the alphabet (refer to part I):

var columnData = table.column(0).data();
var bins = bin( columnData );

$('<span class="clear active"/>')
    .data( 'letter', '' )
    .data( 'match-count', columnData.length )
    .html( 'None' )
    .appendTo( alphabet );

for ( var i=0 ; i<26 ; i++ ) {
    var letter = String.fromCharCode( 65 + i );

    $('<span/>')
        .data( 'letter', letter )
        .data( 'match-count', bins[letter] || 0 )
        .addClass( ! bins[letter] ? 'empty' : '' )
        .html( letter )
        .appendTo( alphabet );
}

Part II completed code

The complete code that is used for the example at the top of this page, including the code that was developed in part I of this series is shown below:

Javascript

var _alphabetSearch = '';

$.fn.dataTable.ext.search.push( function ( settings, searchData ) {
    if ( ! _alphabetSearch ) {
        return true;
    }

    if ( searchData[0].charAt(0) === _alphabetSearch ) {
        return true;
    }

    return false;
} );


function bin ( data ) {
    var letter, bins = {};

    for ( var i=0, ien=data.length ; i<ien ; i++ ) {
        letter = data[i].charAt(0).toUpperCase();

        if ( bins[letter] ) {
            bins[letter]++;
        }
        else {
            bins[letter] = 1;
        }
    }

    return bins;
}


$(document).ready(function() {
    var table = $('#example').DataTable();

    var alphabet = $('<div class="alphabet"/>').append( 'Search: ' );
    var columnData = table.column(0).data();
    var bins = bin( columnData );

    $('<span class="clear active"/>')
        .data( 'letter', '' )
        .data( 'match-count', columnData.length )
        .html( 'None' )
        .appendTo( alphabet );

    for ( var i=0 ; i<26 ; i++ ) {
        var letter = String.fromCharCode( 65 + i );

        $('<span/>')
            .data( 'letter', letter )
            .data( 'match-count', bins[letter] || 0 )
            .addClass( ! bins[letter] ? 'empty' : '' )
            .html( letter )
            .appendTo( alphabet );
    }

    alphabet.insertBefore( table.table().container() );

    alphabet.on( 'click', 'span', function () {
        alphabet.find( '.active' ).removeClass( 'active' );
        $(this).addClass( 'active' );

        _alphabetSearch = $(this).data('letter');
        table.draw();
    } );

    var info = $('<div class="alphabetInfo"></div>')
        .appendTo( alphabet );

    alphabet
        .on( 'mouseenter', 'span', function () {
            info
                .css( {
                    opacity: 1,
                    left: $(this).position().left,
                    width: $(this).width()
                } )
                .html( $(this).data('match-count') )
        } )
        .on( 'mouseleave', 'span', function () {
            info.css('opacity', 0);
        } );
} );

CSS

div.alphabet {
    position: relative;
    display: table;
    width: 100%;
    margin-bottom: 1em;
}

div.alphabet span {
    display: table-cell;
    color: #3174c7;
    cursor: pointer;
    text-align: center;
    width: 3.5%
}

div.alphabet span:hover {
    text-decoration: underline;
}

div.alphabet span.active {
    color: black;
}

div.alphabet span.empty {
    color: red;
}

div.alphabetInfo {
    display: block;
    position: absolute;
    background-color: #111;
    border-radius: 3px;
    color: white;
    top: 2em;
    height: 1.8em;
    padding-top: 0.4em;
    text-align: center;
    z-index: 1;
}

In the concluding part of this series, next week we will take the alphabet control that has been developed here and create a reusable DataTables feature plug-in allowing this input control to be used by any DataTable with a single line of code.