Beginner need an assist on Table data search

[leebond.ia]

Hey W3 Forum,

I am currently building a page that includes a small data set about 400 rows under 3 columns.
I currently am using this function to filter through the three columns based on a search result from an HTML box.
I woulid like to add two things to this function, the first is an ability to filter from a drop down list that
leaves the data unaffected when blank, and a small highlight functionality highlighting whatever 
the current input is.

Could use an assist.

<script Language="javascript">
function searchTable() {
    var input, filter, found, table, tr, td, i, j;
    input = document.getElementById("myInput");
    filter = input.value.toUpperCase();
    table = document.getElementById("myTable");
    tr = table.getElementsByTagName("tr");
    for (i = 0; i < tr.length; i++) {
        td = tr[i].getElementsByTagName("td");
        for (j = 0; j < td.length; j++) {
            if (td[j].innerHTML.toUpperCase().indexOf(filter) > -1) {
                found = true;
            }
        }
        if (found) {
            tr[i].style.display = "";
            found = false;
        } else {
            tr[i].style.display = "none";
        }
    }
}
</script>

 

Edited November 27, 2017 by leebond.ia

[dsonesuk]

You can add argument to function to identify if input, or select to give same result. With the select, you can identify if blank or not and filter or clear filter depending on value. The highlight IF related to td cell can be applied if found equals true when looping through each cell, IF tr is can be applied when found is true same as you have to show row.

[leebond.ia]

Any chance you can refer me to the w3school article that would help me build this? Still very green when it comes to Jscript.