JavaScript: Element.dataset

gistfile1.js

/*  Assuming element:

  <div id="myDiv" data-name="myDiv" data-id="myId" data-my-custom-key="This is the value"></div>

*/

// Get the element
var element = document.getElementById("myDiv");

// Get the id
var id = element.dataset.id;

// Retrieves "data-my-custom-key"
var customKey = element.dataset.myCustomKey;

// Sets the value to something else
element.dataset.myCustomKey = "Some other value";

  // Element becomes:
  //    <div id="myDiv" data-name="myDiv" data-id="myId" data-my-custom-key="Some other value"></div>