JSFiddle - React, Tailwind, and code Playground

HTML

<table name="collection" border="1px">
    <tr name="1">
        <td><input type="checkbox" name="checkmark"></td>
        <td>Tum hi ho</td>
        <td>Arjit singh</td>
    </tr>
    <tr name="2">
        <td><input type="checkbox" name="checkmark"></td>
        <td>Manjha</td>
        <td>Somesh</td>
    </tr>
    <tr name="3">
        <td><input type="checkbox" name="checkmark"></td>
        <td>Ranjhana</td>
        <td>A.R Rehman</td>
    </tr>
</table>

<input type="button" value="Check" onclick="myfunction3()">

JavaScript

function myfunction3(){
    var element_table = document.getElementsByName('collection');
    var element_tableRows = element_table[0].rows;
    var selectedTr = new Array();
    var data = "";
    for(var i =0 ; i < element_tableRows.length;i++)
    {
        var checkerbox = element_tableRows[i].cells[0].firstChild;
        if(checkerbox.checked){
            //selectedTr[selectedTr.length] = element_tableRows[i].getAttribute("name"); //not sure what you want with this
            data = data + element_tableRows[i].getAttribute("name");
        }
    }
    var element_paragraph = document.getElementsByName('description');
    element_paragraph.innerHTML = data;
    alert(data);
}