Array

<input type='text' id='S_NAME' name='DATA[S_NAME]' class='symbolic' value='<?=$postArData['S_NAME']?>' data-check='["test", "twoo", "thrie"]' />
var stuff = $("#S_NAME").data("check");
alert(stuff[2]);

Object

<input type='text' id='S_NAME' name='DATA[S_NAME]' class='symbolic' value='<?=$postArData['S_NAME']?>' data-check='{"name":"John"}' />
var stuff = $("#S_NAME").data("check");
console.log(stuff);