//<div id="myElementID" data-myvalue="37"></div>
var a = $('#myElementID').data('myvalue'); //get myvalue
$('#myElementID').data('myvalue',38); //set myvalue//set the custom data value
let mainDiv = $('#yourDivId').data('anyName', value);
//access the custom data value
mainDiv.data('anyName');
alert($('#outer').html()); // alerts <div id="mydiv" data-myval="10"> </div>
var a = $('#mydiv').data('myval'); //getter
$('#mydiv').attr("data-myval","20"); //setter
alert($('#outer').html()); //alerts <div id="mydiv" data-myval="20"> </div>//sometimes it is better to use JS
<script>
// 'Getting' data-attributes using getAttribute
var plant = document.getElementById('strawberry-plant');
var fruitCount = plant.getAttribute('data-fruit'); // fruitCount = '12'
// 'Setting' data-attributes using setAttribute
plant.setAttribute('data-fruit','7'); // Pesky birds
</script>