checkbox 全选、全不选、子项全选则全选按钮也选中

HTML:

<input type="checkbox" class="fl"  name = "allBirthDate" onclick="checkAll('checkBirthDate',event)"/>全选</span>

<input type="checkbox" name="checkBirthDate" onclick="checkItem('allBirthDate',event)"/>

JS:

// 表格全选，反选

function checkAll(str, ev) {
var a = document.getElementsByName(str);
var n = a.length;
var target = ev.srcElement || ev.target;
for (var i = 0; i < n; i++)
a[i].checked = target.checked;

}

function checkItem(str, ev) {
var e = ev.srcElement || ev.target;
var all = eval("document.all." + str);
if (e.checked) {
var a = document.getElementsByName(e.name);
all.checked = true;
for (var i = 0; i < a.length; i++) {
if (!a[i].checked) {
all.checked = false;
break;
}
}
} else
all.checked = false;

}