You have a couple of errors there:
1. invalid for loop:
for (j = 0; j < tr.width; j++)
There's no such thing as tr.width. Or rather it's a jQuery function, so you're getting a text of it when you type tr.width.
Thus the script breaks, since the for loop clause if invalid.
If you actually called like this tr.width() you would get the pixel width of the element so it wouldn't help you either.
What you need is the <td> count in it. Here's how you get it:
let rowTds = tr[i].getElementsByTagName("td")
for (j = 0; j < rowTds.length; j++){...}
now you can iterate through the all the <td>s in the row.
2. Hide row logic needs revision to multiple column check:
Now you also need to change the logic of the hiding because it will keep hiding a row if the the last <td> didn't match the filter string.
td = tr[i].getElementsByTagName("td")[j];
if (td) {
if (td.innerHTML.toUpperCase().indexOf(filter) > -1) {
tr[i].style.display = "";
break; // this will break the row looping on j after making the row visible.
} else {
tr[i].style.display = "none";
}
}
}
}
}
Conclusion: Full working code adjusted from the W3schools tutorial:
Link: https://www.w3schools.com/code/tryit.asp?filename=FVXZWZMELE1Q
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<script
src="https://code.jquery.com/jquery-3.3.1.min.js"
integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8="
crossorigin="anonymous"></script>
<style>
* {
box-sizing: border-box;
}
#myInput {
background-image: url('/css/searchicon.png');
background-position: 10px 10px;
background-repeat: no-repeat;
width: 100%;
font-size: 16px;
padding: 12px 20px 12px 40px;
border: 1px solid #ddd;
margin-bottom: 12px;
}
#myTable {
border-collapse: collapse;
width: 100%;
border: 1px solid #ddd;
font-size: 18px;
}
#myTable th, #myTable td {
text-align: left;
padding: 12px;
}
#myTable tr {
border-bottom: 1px solid #ddd;
}
#myTable tr.header, #myTable tr:hover {
background-color: #f1f1f1;
}
</style>
</head>
<body>
<h2>My Customers</h2>
<input type="text" id="myInput" onkeyup="myFunction()" placeholder="Search for names.." title="Type in a name">
<table id="myTable">
<tr class="header">
<th style="width:60%;">Name</th>
<th style="width:40%;">Country</th>
</tr>
<tr>
<td>Alfreds Futterkiste</td>
<td>Germany</td>
</tr>
<tr>
<td>Berglunds snabbkop</td>
<td>Sweden</td>
</tr>
<tr>
<td>Island Trading</td>
<td>UK</td>
</tr>
<tr>
<td>Koniglich Essen</td>
<td>Germany</td>
</tr>
<tr>
<td>Laughing Bacchus Winecellars</td>
<td>Canada</td>
</tr>
<tr>
<td>Magazzini Alimentari Riuniti</td>
<td>Italy</td>
</tr>
<tr>
<td>North/South</td>
<td>UK</td>
</tr>
<tr>
<td>Paris specialites</td>
<td>France</td>
</tr>
</table>
<script>
function myFunction() {
var input, filter, table, tr, td, i;
input = document.getElementById("myInput");
filter = input.value.toUpperCase();
table = document.getElementById("myTable");
tr = table.getElementsByTagName("tr");
for (i = 0; i < tr.length; i++) {
let rowTds = tr[i].getElementsByTagName("td")
for (j = 0; j < rowTds.length; j++){
td = tr[i].getElementsByTagName("td")[j];
if (td) {
if (td.innerHTML.toUpperCase().indexOf(filter) > -1) {
tr[i].style.display = "";
break;
} else {
tr[i].style.display = "none";
}
}
}
}
}
</script>
</body>
</html>
trtodisplay: none. Otherwise, subsequent cells that don't match your filter will reset the display value.