como cambiar codigo javascript a jquery puro

[dontexplain]

for(var i = 0 ; i < document.getElementsByName("chk").length; i++)
calcular(document.getElementsByName("chk")[i], 1);
}


######################

d=$("chk");
$.each(d,function(i,v){
calcular($(v),1);
});


-----------------------------------

function calcular(obj, opc){
if(opc==1)
obj.checked = (document.getElementById("chk_todos").checked==tru e)?true:false;
var val = (obj.checked == true)? obj.id.split("_")[1] : 0;
obj.value = val;
document.getElementById("text_"+ obj.id.split("_")[1]).value = val;
}

####################################

function calcular(obj, opc){
if(opc==1){

$(obj).attr("checked") = ($("#chk_todos").attr("checked")==true)? true : false;
var val = ( $(obj).attr("checked") == true)? $(obj).attr("id").split("_")[1] : 0;
$(obj).val(val);
$("#text_"+$(obj).attr("id").split("_")[1]).val(val);
}

}

Un saludo.