#! code

Using server side scripts to search for things can be as complex or as simple as the situation requires. However, if you have a table of results and you just want to enable a simple JavaScript search on that table then this might be the script for you.

To search a table using JavaScript you need to split the table into bits, this can be done using the getElementsByTagName() function, which takes the name of the element that you want to capture. So to grab all of the rows of a table as an array you need to pass the value of tr.

var rows = document.getElementsByTagName("tr");

We can then iterate through these rows, grabbing the column that you want to search on, with the following code.

for ( var i = 0; i < rows.length; i++ ) {
  var fullname = rows[i].getElementsByTagName("td");
  fullname = fullname[0].innerHTML.toLowerCase();
}

Before we can go any further we need a form so that the user can enter information and a table that can be used to search. First the form, the action of the input box will cause a function called doSearch() to be run, this will contain our search code.

<form action="#" method="get" onsubmit="return false;">
<input type="text" size="30" name="q" id="q" value="" onkeyup="doSearch();" />
</form>

Next, the table. Note that I have added an additional row to the end of this table. This will be used to display a note to the user if they have entered a query that isn't found.

<table>
<tr><td>One</td></tr>
<tr><td>Two</td></tr>
<tr><td>Three</td></tr>
<tr><td>Four</td></tr>
<tr><td>Five</td></tr>
<tr><td>Six</td></tr>
<tr><td>Seven</td></tr>
<tr><td>Eight</td></tr>
<tr style="display:none;" id="noresults"> 
 <td>(no listings that start with "<span id="qt"></span>")</td> 
</tr>
</table>

The first thing we need to do in our search function is to prepare the search term. This turns the query string to lowercase, which we can then match to the table column.

var q = document.getElementById("q");
var v = q.value.toLowerCase();

Now we can go through each row value and try to match it to the value in the query string. If it matches then we display the row, if not then we hide it.

  for ( var i = 0; i < rows.length; i++ ) {
    var fullname = rows[i].getElementsByTagName("td");
    fullname = fullname[0].innerHTML.toLowerCase();
    if ( fullname ) {
        if ( v.length == 0 || (v.length < 3 && fullname.indexOf(v) == 0) || (v.length >= 3 && fullname.indexOf(v) > -1 ) ) {
        rows[i].style.display = "";
      } else {
        rows[i].style.display = "none";
      }
    }
  }

Here is the full function, including the code to implement the no results note.

<script type="text/javascript">
//<!--
function doSearch() {
  var q = document.getElementById("q");
  var v = q.value.toLowerCase();
  var rows = document.getElementsByTagName("tr");
  var on = 0;
  for ( var i = 0; i < rows.length; i++ ) {
    var fullname = rows[i].getElementsByTagName("td");
    fullname = fullname[0].innerHTML.toLowerCase();
    if ( fullname ) {
        if ( v.length == 0 || (v.length < 3 && fullname.indexOf(v) == 0) || (v.length >= 3 && fullname.indexOf(v) > -1 ) ) {
        rows[i].style.display = "";
        on++;
      } else {
        rows[i].style.display = "none";
      }
    }
  }
  var n = document.getElementById("noresults");
  if ( on == 0 && n ) {
    n.style.display = "";
    document.getElementById("qt").innerHTML = q.value;
  } else {
    n.style.display = "none";
  }
}
//-->
</script>

Here is a working example of the code, with valid HTML.