<input type="checkbox" id="selectAll" onclick="checkAll()">全選
function checkAll()
{
var checkedOfAll=$("#selectAll").prop("checked");
alert(checkedOfAll);
$("input[name='procheck']").prop("checked", checkedOfAll);
}

<input type="checkbox" id="selectAll" onclick="checkAll()" >全選

<input type="checkbox" id="selectAll" onclick="checkAll()" checked>全選
function checkAll()
{
var checkedOfAll=$("#selectAll").attr("checked");
alert(checkedOfAll);
$("input[name='procheck']").attr("checked", checkedOfAll);
}