select2 multiple only one selected value issue in jquery code example

Example 1: jquery select2 multiple select all

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

Example 2: how to select multiple jquery element at once

// To select multiple html element at once using jquery, follow the syntax below
$("tagName1, tagName2, tageName3")
// The above code will select "tagName1", "tagName2", tagName3


// To select multiple element using "class name" follow the syntax below
$(".className1, .className2, .className3, .className4")

// To select multiple element using "id name" follow the syntax below
$("#idName1, #idName2")