Save button in a simple CRUD application should appear only when I update or edit

This application has Add,Edit And Delete Rows From Table Dynamically Using JavaScript.

Just cant find the solution how the Save Button will appear only when click the Edit. The current state is after you Add a row, theres a button Save there which is unusable. I tried removing this input tag within the add_row() function, var row :

<input type='button' id='save_button"+table_len+"' value='Save' class='save' onclick='save_row("+table_len+")'>

But the save button will also not available when you Edit.

please see my code, ** Thank you so much **

<html>
<head>
<script type="text/javascript">

function edit_row(no)
{
 document.getElementById("edit_button"+no).style.display="none";
 document.getElementById("save_button"+no).style.display="block";
    
 var name=document.getElementById("name_row"+no);
 var country=document.getElementById("country_row"+no);
 var age=document.getElementById("age_row"+no);
    
 var name_data=name.innerHTML;
 var country_data=country.innerHTML;
 var age_data=age.innerHTML;
    
 name.innerHTML="<input type='text' id='name_text"+no+"' value='"+name_data+"'>";
 country.innerHTML="<input type='text' id='country_text"+no+"' value='"+country_data+"'>";
 age.innerHTML="<input type='text' id='age_text"+no+"' value='"+age_data+"'>";
}

function save_row(no)
{
 var name_val=document.getElementById("name_text"+no).value;
 var country_val=document.getElementById("country_text"+no).value;
 var age_val=document.getElementById("age_text"+no).value;

 document.getElementById("name_row"+no).innerHTML=name_val;
 document.getElementById("country_row"+no).innerHTML=country_val;
 document.getElementById("age_row"+no).innerHTML=age_val;

 document.getElementById("edit_button"+no).style.display="block";
 document.getElementById("save_button"+no).style.display="none";
}

function delete_row(no)
{
 document.getElementById("row"+no+"").outerHTML="";
}

function add_row()
{
 var new_name=document.getElementById("new_name").value;
 var new_country=document.getElementById("new_country").value;
 var new_age=document.getElementById("new_age").value;
    
 var table=document.getElementById("data_table");
 var table_len=(table.rows.length)-1;
 var row = table.insertRow(table_len).outerHTML="<tr id='row"+table_len+"'><td id='name_row"+table_len+"'>"+new_name+"</td><td id='country_row"+table_len+"'>"+new_country+"</td><td id='age_row"+table_len+"'>"+new_age+"</td><td><input type='button' id='edit_button"+table_len+"' value='Edit' class='edit' onclick='edit_row("+table_len+")'> <input type='button' id='save_button"+table_len+"' value='Save' class='save' onclick='save_row("+table_len+")'> <input type='button' value='Delete' class='delete' onclick='delete_row("+table_len+")'></td></tr>";

 document.getElementById("new_name").value="";
 document.getElementById("new_country").value="";
 document.getElementById("new_age").value="";
}</script>
</head>
<body>
<div id="wrapper">
<table align='center' cellspacing=2 cellpadding=5 id="data_table" border=1>
<tr>
<th>Name</th>
<th>Country</th>
<th>Age</th>
</tr>

<tr id="row1">
<td id="name_row1">Name1</td>
<td id="country_row1">Country1</td>
<td id="age_row1">22</td>
<td>
<input type="button" id="edit_button1" value="Edit" class="edit" onclick="edit_row('1')">
<input type="button" id="save_button1" value="Save" class="save" onclick="save_row('1')">
<input type="button" value="Delete" class="delete" onclick="delete_row('1')">
</td>
</tr>

<tr id="row2">
<td id="name_row2">Name2</td>
<td id="country_row2">Country2</td>
<td id="age_row2">21</td>
<td>
<input type="button" id="edit_button2" value="Edit" class="edit" onclick="edit_row('2')">
<input type="button" id="save_button2" value="Save" class="save" onclick="save_row('2')">
<input type="button" value="Delete" class="delete" onclick="delete_row('2')">
</td>
</tr>

<tr id="row3">
<td id="name_row3">Name3</td>
<td id="country_row3">Country3</td>
<td id="age_row3">24</td>
<td>
<input type="button" id="edit_button3" value="Edit" class="edit" onclick="edit_row('3')">
<input type="button" id="save_button3" value="Save" class="save" onclick="save_row('3')">
<input type="button" value="Delete" class="delete" onclick="delete_row('3')">
</td>
</tr>

<tr>
<td><input type="text" id="new_name"></td>
<td><input type="text" id="new_country"></td>
<td><input type="text" id="new_age"></td>
<td><input type="button" class="add" onclick="add_row();" value="Add Row"></td>
</tr>

</table>
</div>

</body>
</html>
``