select2.select code example

Example 1: select2.org events

$('#mySelect2').on('select2:select', function (e) {
    var data = e.params.data;
    console.log(data);
});

Example 2: jquery select2 multiple select all

$("#checkbox").click(function(){
    if($("#checkbox").is(':checked') ){
        $("select > option").prop("selected","selected");
    }else{
        $("select > option").removeAttr("selected");
     }
});