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The following code that I typed is used to add or delete rows in an html table. When I click the add button without any problem, but when I click the delete button though I want to delete a particular row I am unable to. I get an alert message stating:
"can not read property `onclick` of null "
How can I rectify this issue?
<HTML>
<HEAD>
<TITLE> Add/Remove dynamic rows in HTML table </TITLE>
<SCRIPT language="javascript">
function addRow(tableID) {
var table = document.getElementById(tableID);
var rowCount = table.rows.length;
var row = table.insertRow(rowCount);
var colCount = table.rows[0].cells.length;
for (var i = 0; i < colCount; i++) {
var newcell = row.insertCell(i);
newcell.innerHTML = table.rows[0].cells[i].innerHTML;
//alert(newcell.childNodes);
switch (newcell.childNodes[0].type) {
case "text":
newcell.childNodes[0].value = "";
break;
case "checkbox":
newcell.childNodes[0].checked = false;
break;
case "select-one":
newcell.childNodes[0].selectedIndex = 0;
break;
}
}
}
function deleteRow(tableID) {
try {
var table = document.getElementById(tableID);
var rowCount = table.rows.length;
for (var i = 0; i < rowCount; i++) {
var row = table.rows[i];
var chkbox = row.cells[0].childNodes[0];
if (document.getElementById('button').onclick == true) {
if (rowCount <= 1) {
alert("Cannot delete all the rows.");
break;
}
table.deleteRow(i);
rowCount--;
i--;
}
}
} catch (e) {
alert(e);
}
}
</SCRIPT>
</HEAD>
<BODY>
<INPUT type="button" value="Add Row" onclick="addRow('dataTable')" />
<TABLE id="dataTable" width="350px" border="1">
<TR>
<TD>
<INPUT type="button" name="button" value=delete id=delete onclick="deleteRow('dataTable')">
</TD>
</TR>
</TABLE>
</BODY>
</HTML>
The following code that I typed is used to add or delete rows in an html table. When I click the add button without any problem, but when I click the delete button though I want to delete a particular row I am unable to. I get an alert message stating:
"can not read property `onclick` of null "
How can I rectify this issue?
<HTML>
<HEAD>
<TITLE> Add/Remove dynamic rows in HTML table </TITLE>
<SCRIPT language="javascript">
function addRow(tableID) {
var table = document.getElementById(tableID);
var rowCount = table.rows.length;
var row = table.insertRow(rowCount);
var colCount = table.rows[0].cells.length;
for (var i = 0; i < colCount; i++) {
var newcell = row.insertCell(i);
newcell.innerHTML = table.rows[0].cells[i].innerHTML;
//alert(newcell.childNodes);
switch (newcell.childNodes[0].type) {
case "text":
newcell.childNodes[0].value = "";
break;
case "checkbox":
newcell.childNodes[0].checked = false;
break;
case "select-one":
newcell.childNodes[0].selectedIndex = 0;
break;
}
}
}
function deleteRow(tableID) {
try {
var table = document.getElementById(tableID);
var rowCount = table.rows.length;
for (var i = 0; i < rowCount; i++) {
var row = table.rows[i];
var chkbox = row.cells[0].childNodes[0];
if (document.getElementById('button').onclick == true) {
if (rowCount <= 1) {
alert("Cannot delete all the rows.");
break;
}
table.deleteRow(i);
rowCount--;
i--;
}
}
} catch (e) {
alert(e);
}
}
</SCRIPT>
</HEAD>
<BODY>
<INPUT type="button" value="Add Row" onclick="addRow('dataTable')" />
<TABLE id="dataTable" width="350px" border="1">
<TR>
<TD>
<INPUT type="button" name="button" value=delete id=delete onclick="deleteRow('dataTable')">
</TD>
</TR>
</TABLE>
</BODY>
</HTML>
- 'onclick' is an event, you have to assign a function there. The event will never be 'true' like this or anything else (value). It will just points to a function – llouk Commented Oct 13, 2016 at 7:26
- how to correct it? – Amal Commented Oct 13, 2016 at 7:27
- I dont know what you are trying to do over there. Just remove that 'if' statement – llouk Commented Oct 13, 2016 at 7:29
-
What's the point of that
ifstatement? There is noid="button"in your HTML. – Barmar Commented Oct 13, 2016 at 7:29 - By the way your delete button's id is 'delete' as I can see not 'button'. Missing quotes as well there – llouk Commented Oct 13, 2016 at 7:31
6 Answers
Reset to default 1The easiest way I've found to handle scenarios like these is to work with classes instead of ids, and also to use context. IDs are used as unique identifiers for items on your page. Because you will very likely have more than one 'remove button' on your page, it would be best to target them using a class name instead.
So what I would do if I were you is to include jQuery, it would make things a lot simpler for you.
Add the below line in your html document before the closing body tag.
<script src="https://ajax.googleapis./ajax/libs/jquery/3.1.1/jquery.min.js"></script>
Add a 'removeRowBtn' class to your 'remove buttons'. Then, for removing a row:
$(document).ready(function(){
$('body').on('click', '.removeRowBtn', function(){
// to make sure at least one row remains
if($('.removeRowBtn').length > 0){
$(this).parents('tr').remove();
}
});
});
And that's all you need. The above code uses context to target the parent row of the 'remove button' you are clicking on. No need to specify which table, calculate which row or how many rows are left etc.
First things first document.getElementById('button') returns undefined because you have no element in your page with id=button.
That is the error you are getting, but I think you should approach the deletion of your table rows slightly different.
The easiest way is this:
function deleteRow(elem) {
var table = elem.parentNode.parentNode.parentNode;
var rowCount = table.rows.length;
if(rowCount === 1) {
alert('Cannot delete the last row');
return;
}
// get the "<tr>" that is the parent of the clicked button
var row = elem.parentNode.parentNode;
row.parentNode.removeChild(row); // remove the row
}
and use this function as the click event handler on each button:
<table>
<tr>
<td><button onclick="deleteRow(this)">delete</button></td>
</tr>
</table>
There's no need to create deleteRow(tableID) because by doing this you are trying to override the default deleteRow function of javascript so instead of creating a deleteRow(tableID) just add 'document.getElementById('dataTable').deleteRow(this.rowIndex)' to onclick of the delete button
<input type="button" name="button" value=delete id=delete onclick="document.getElementById('dataTable').deleteRow(this.rowIndex)">
You can use below method to delete a particular row.
SCRIPT METHOD:
function deleteRow(element,tableID) {
try {
var tableElement = document.getElementById(tableID);
if(tableElement.rows.length <= 1){
alert("Cannot delete all the rows.");
return;
}
var x = element.parentElement;//td tag
x = x.parentElement;// tr tag
x.remove();
}catch(e) {
alert(e);
}
}
BUTTON ELEMENT IN TD
<TD><INPUT type="button" name="button" value=delete id=delete onclick="deleteRow(this,'dataTable')"></TD>
<div class="table-responsive">
<table class="table" id="testTable">
<thead>
<tr>
<th>Col1</th>
<th>Col2</th>
<th>Type</th>
<th>Remove</th>
</tr>
</thead>
<tbody>
<tr>
<td><input type="text" id="mainScript" name="mainScript"></td>
<td><input type="text" id="rollBackScript" name="rollBackScript"></td>
<td><select name="type" id ="type" >
<option value="Automated" selected >Automated</option>
<option value="Manual" >Manual</option>
</select>
</td>
<td><input type="button" class="btn btn-danger" value="Delete" onclick="deleteRow(this);"></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="row" align="left">
<input type="button" class="btn btn-success" value="Add Row" onclick="addRow('scriptsTable')" />
</div>
JavaScript functions
<script>
function addRow(tableId) {
var table = document.getElementById(tableId);
var rowCount = table.rows.length;
var row = table.insertRow(rowCount);
var colCount = table.rows[1].cells.length;
for(var i=0; i<colCount; i++) {
var newcell = row.insertCell(i);
newcell.innerHTML = table.rows[1].cells[i].innerHTML;
//alert(newcell.childNodes);
switch(newcell.childNodes[0].type) {
case "text":
newcell.childNodes[0].value = "";
break;
case "checkbox":
newcell.childNodes[0].checked = false;
break;
case "select-one":
newcell.childNodes[0].selectedIndex = 0;
break;
case "button":
newcell.childNodes[0].value = "Delete";
break;
}
}
}
function deleteRow(deleteBtn) {
var table = document.getElementById('scriptsTable');
if(table.rows.length <= 2){
alert("Cannot delete all the rows.");
return;
}
if (typeof(deleteBtn) == "object") {
$(deleteBtn).closest("tr").remove();
} else {
return false;
}
}
</script>
Try this one. this is working example
<table id="example" class="table table-striped table-bordered" cellspacing="0" width="100%">
<thead>
<tr>
<th>ID</th>
<th>Name</th>
<th>Position</th>
<th>Action</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>Tiger Nixon</td>
<td>System Architect</td>
<td><button>Delete</button></td>
</tr>
</tbody>
</table>
<script>
$(document).ready(function () {
var table = $('#example').DataTable({
"columns": [
null,
null,
null,
{
"sortable": false
}
]
});
});
$('#example').on("click", "button", function(){
console.log($(this).parent());
table.row($(this).parents('tr')).remove().draw(false);
});
</script>
本文标签： javascriptDeleting a table row from button clickStack Overflow
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