Take the 2-minute tour ×
Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It's 100% free, no registration required.

The following code sorts an HTML table with Javascript (without using any external libraries like JQuery). Are there any shortcomings or possible improvements I could make?

<html>

<head>
    <meta http-equiv="content-type" content="text/html;charset=Windows-1252">
    <script type="text/javascript">
        var people, asc1 = 1,
            asc2 = 1,
            asc3 = 1;
        window.onload = function () {
            people = document.getElementById("people");
        }

        function sort_table(tbody, col, asc) {
            var rows = tbody.rows,
                rlen = rows.length,
                arr = new Array(),
                i, j, cells, clen;
            // fill the array with values from the table
            for (i = 0; i < rlen; i++) {
                cells = rows[i].cells;
                clen = cells.length;
                arr[i] = new Array();
                for (j = 0; j < clen; j++) {
                    arr[i][j] = cells[j].innerHTML;
                }
            }
            // sort the array by the specified column number (col) and order (asc)
            arr.sort(function (a, b) {
                return (a[col] == b[col]) ? 0 : ((a[col] > b[col]) ? asc : -1 * asc);
            });
            // replace existing rows with new rows created from the sorted array
            for (i = 0; i < rlen; i++) {
                rows[i].innerHTML = "<td>" + arr[i].join("</td><td>") + "</td>";
            }
        }
    </script>
    <style type="text/css">
        table {
            border-collapse: collapse;
            border: none;
        }
        th,
        td {
            border: 1px solid black;
            padding: 4px 16px;
            font-family: Times New Roman;
            font-size: 24px;
            text-align: left;
        }
        th {
            background-color: #C8C8C8;
            cursor: pointer;
        }
    </style>
</head>

<body>
    <table>
        <thead>
            <tr>
                <th onclick="sort_table(people, 0, asc1); asc1 *= -1; asc2 = 1; asc3 = 1;">Name</th>
                <th onclick="sort_table(people, 1, asc2); asc2 *= -1; asc3 = 1; asc1 = 1;">Surname</th>
                <th onclick="sort_table(people, 2, asc3); asc3 *= -1; asc1 = 1; asc2 = 1;">Age</th>
            </tr>
        </thead>
        <tbody id="people">
            <tr>
                <td>Raja</td>
                <td>Dey</td>
                <td>18</td>
            </tr>
            <tr>
                <td>Mamata</td>
                <td>Sharma</td>
                <td>20</td>
            </tr>
            <tr>
                <td>Avijit</td>
                <td>Sharma</td>
                <td>21</td>
            </tr>
            <tr>
                <td>Sharanya</td>
                <td>Dutta</td>
                <td>26</td>
            </tr>
            <tr>
                <td>Nabin</td>
                <td>Roy</td>
                <td>27</td>
            </tr>
        </tbody>
    </table>
</body>

</html>

share|improve this question

migrated from stackoverflow.com Dec 17 '13 at 22:19

This question came from our site for professional and enthusiast programmers.

5  
Is the code otherwise working? If you're looking for just feedback, you should post to Code Review instead. –  Juhana Dec 17 '13 at 9:37
    
Why not use Jquery. You can use tablesorter plugin. tablesorter.com/docs/example-pager.html –  Anup Dec 17 '13 at 10:14
    
His code is working (it only had a misconfiguration on jsfiddle: jsfiddle ) and he is asking for performance tips. @Anup : (without any external library like JQuery) –  ProGM Dec 17 '13 at 10:20

3 Answers 3

up vote 4 down vote accepted

To speed up the sorting you first have to find what is consuming time. In your case the slower part of your code is:

for(i = 0; i < rlen; i++){
    rows[i].innerHTML = "<td>"+arr[i].join("</td><td>")+"</td>";
}

The reason is that the DOM elaboration is time consuming for the browser.

Here's an updated version that minimizes the access to the DOM:

function sort_table(tbody, col, asc){
    var rows = tbody.rows, rlen = rows.length, arr = new Array(), i, j, cells, clen;
    // fill the array with values from the table
    for(i = 0; i < rlen; i++){
    cells = rows[i].cells;
    clen = cells.length;
    arr[i] = new Array();
        for(j = 0; j < clen; j++){
        arr[i][j] = cells[j].innerHTML;
        }
    }
    // sort the array by the specified column number (col) and order (asc)
    arr.sort(function(a, b){
        return (a[col] == b[col]) ? 0 : ((a[col] > b[col]) ? asc : -1*asc);
    });
    for(i = 0; i < rlen; i++){
        arr[i] = "<td>"+arr[i].join("</td><td>")+"</td>";
    }
    tbody.innerHTML = "<tr>"+arr.join("</tr><tr>")+"</tr>";
}

Proof: http://jsperf.com/table-sorting-stack-overflow

share|improve this answer

Here is the pure JS for sorting table data. I used first column which holds numbers. You have to modify column index and condition statement as per your requirements. I hope that solves your problem...

    // Table data sorting starts....
    function sortData(){
        // Read table body node.
        var tableData = document.getElementById('data_table').getElementsByTagName('tbody').item(0);

        // Read table row nodes.
        var rowData = tableData.getElementsByTagName('tr'); 

        for(var i = 0; i < rowData.length - 1; i++){
            for(var j = 0; j < rowData.length - (i + 1); j++{

                //Swap row nodes if short condition matches
                if(parseInt(rowData.item(j).getElementsByTagName('td').item(0).innerHTML) > parseInt(rowData.item(j+1).getElementsByTagName('td').item(0).innerHTML)){
                    tableData.insertBefore(rowData.item(j+1),rowData.item(j));
                }
            }
        }
    }
    // Table data sorting ends....

HTML Table:

    <table id="data_table" width="200" border="1">
        <tbody>
        <tr>
            <td width="100">01</td>
            <td>aaa</td>
        </tr>
        <tr>
            <td>04</td>
            <td>ddd</td>
        </tr>
        <tr>
            <td>05</td>
            <td>eee</td>
        </tr>
        <tr>
            <td>03</td>
            <td>ccc</td>
        </tr>
        <tr>
            <td>02</td>
            <td>bbb</td>
        </tr>
        <tr>
            <td>06</td>
            <td>fff</td>
        </tr>
        </tbody>
    </table>

HTML Table: Sorted

    <table id="data_table" width="200" border="1">
        <tbody>
        <tr>
            <td width="100">01</td>
            <td>aaa</td>
        </tr>
        <tr>
            <td>02</td>
            <td>bbb</td>
        </tr>
        <tr>
            <td>03</td>
            <td>ccc</td>
        </tr>
        <tr>
            <td>04</td>
            <td>ddd</td>
        </tr>
        <tr>
            <td>05</td>
            <td>eee</td>
        </tr>
        <tr>
            <td>06</td>
            <td>fff</td>
        </tr>
        </tbody>
    </table>

Here is demo.

share|improve this answer
    
This whole answer is all jquery. Although I think it's great you answered, the OP was asking specifically for non jquery solutions. –  dreza Dec 21 '13 at 5:33
    
Here you go. Pure JS code for sorting HTML nodes. You can see the demo on given link. –  BwithLove Dec 22 '13 at 11:18

I ran into some trouble with ProGM's solution.

  1. It didn't take numerical sorting into account.
  2. IE did NOT like setting this line: tbody.innerHTML = "<tr>"+arr.join("</tr><tr>")+"</tr>";
  3. It would destroy any attributes assigned to any part of the table (css class names and etc)

I have made adjustments:

function sort_table(tbody, col, asc)
{
    var rows = tbody.rows;
    var rlen = rows.length;
    var arr = new Array();
    var i, j, cells, clen;
    // fill the array with values from the table
    for(i = 0; i < rlen; i++)
    {
        cells = rows[i].cells;
        clen = cells.length;
        arr[i] = new Array();
      for(j = 0; j < clen; j++) { arr[i][j] = cells[j].innerHTML; }
    }
    // sort the array by the specified column number (col) and order (asc)
    arr.sort(function(a, b)
    {
        var retval=0;
        var fA=parseFloat(a[col]);
        var fB=parseFloat(b[col]);
        if(a[col] != b[col])
        {
            if((fA==a[col]) && (fB==b[col]) ){ retval=( fA > fB ) ? asc : -1*asc; } //numerical
            else { retval=(a[col] > b[col]) ? asc : -1*asc;}
        }
        return retval;      
    });
    for(var rowidx=0;rowidx<rlen;rowidx++)
    {
        for(var colidx=0;colidx<arr[rowidx].length;colidx++){ tbody.rows[rowidx].cells[colidx].innerHTML=arr[rowidx][colidx]; }
    }
}

To address point #1, I added in the calls to parseFloat() and then compared the result the original value (You change to checking if it produces NaN instead). If both values are numeric, they compared via numerical preference and not by their string versions.

For points #2 and #3, I solved it via the same set of code. Instead of destroying the whole table body by setting the innerHTML, I change the individual cell contents to the new sorted values:

for(var rowidx=0;rowidx<rlen;rowidx++)
{
    for(var colidx=0;colidx<arr[rowidx].length;colidx++)
    { 
        tbody.rows[rowidx].cells[colidx].innerHTML=arr[rowidx][colidx]; 
    }
}

That only works if yours all have the same number of columns, but if you do not, sorting is much more complex anyway.

share|improve this answer
    
will you explain the adjustments please and how they overcome the issues that you found? –  Malachi Nov 10 '14 at 17:12
1  
Can do, I also found a mistake in mine. –  Plater Nov 11 '14 at 13:51

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.