jquery implements function codes such as checkbox selection, inverse selection, and no selection (odd number)_jquery

Apple
Orange
Banana
Grape

$(function(){
$('#btn1').click(function(){//Select all
$("[name='fruit']").attr('checked','true');
} );
$('#btn2').click(function(){//Select none
$("[name='fruit']").removeAttr('checked');
});
$('#btn3').click(function(){//Inverse selection
$("[name='fruit']").each(function(){
if( $(this).attr('checked')){
$(this).removeAttr('checked');
}else{
$(this).attr('checked','true ');
}
})
});
$("#btn4").click(function(){//Select all odd numbers
$("[name=' fruit']:even").attr('checked','true');
})
$("#btn5").click(function(){//Get the values ​​of all selected options
var checkVal='';
$("[name='fruit'][checked]").each(function(){
checkVal =$(this).val() ',' ;
})
alert(checkVal);
})
});