JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td style="width:5px;">
            <input type="button" id="GridView1__ctl2_AddButton0" name="GridView1:_ctl2:AddButton0" value="On" class="btn-blue" onclick="setDateTimeOn(this)">
        </td>
        <td style="width:150px;">
           <!-- <input id="GridView1__ctl2_txtStormTimeOn" type="text" name="GridView1:_ctl2:txtStormTimeOn" value="">-->
            <span id="GridView1__ctl2_lblStormTimeOn"></span> 
        </td>
    </tr>
</table>

JavaScript

//  txtLevel1Issued.Text = DateTime.Now.ToString("M/d/yyyy HH:mm");

var date = new Date();
//alert((date.getMonth() + 1) + '-' + date.getDate() + '-' +  date.getFullYear());



//GridView1__ctl2_AddButton0
//GridView1:_ctl2:txtStormTimeOn

//09-11-2015 10:03


function setDateTimeOn(elm) {
    var formattedDate = GetCurrentDateTime(); //get formatted date
    $(elm) //clicked button
        .parent("td") // container td
        .next() // next td
        //.find("input") // find child input
         .find("span")
        .text(formattedDate); //set date
}

//var t = new Date();
//alert(hours12(t));

function GetCurrentDateTime() {
    var now = new Date();
    var h12 = hours12(now); 
    return (now.getMonth() + 1) + "-" 
        + now.getDate() + "-" 
        + now.getFullYear() + " " 
        //+ now.getHours() + ":" 
    	+ h12 + ":"
        + now.getMinutes();
}


function hours12(date) { return (date.getHours() + 24) % 12 || 12; }


function setDateTimeOnOLD(x) {

    
    
    //alert(x.id);   
    console.log(x.id);
    //$('#x.id').val(

    var re = /__(.+)_/;
    // your control name was used an as example:
    //var str = 'GridView1__ctl2_AddButton0';

    var str = x.id;
    var m;

    if ((m = re.exec(str)) !== null) {
        if (m.index === re.lastIndex) {
            re.lastIndex++;
        }
        // View your result using the m-variable.
        // m[0] == 'ctl2'

        //$('[id^=conditionValue]').each(function (y) {


        $("#GridView1"+ m[0] + "txtStormTimeOn").val("whatever");
        
        
        var z = m[0].replace('__', '');
        var z = z.replace('_', '');
        console.log(z);
        //console.log(m[0]);
		
    }






}