js全选实现和判断是否有复选框选中

function actionEvent(methodname){var form = document.forms[0];if(validateIsSelect(form.all, form.productids)){form.action='<html:rewrite action="/control/product/manage"/>';form.submit();}else{alert("请选择要操作的记录");}}function allselect(allobj,items){    var state = allobj.checked;    if(items.length){    for(var i=0;i<items.length;i++){    if(!items[i].disabled) items[i].checked=state;    }    }else{    if(!items[i].disabled) items.checked=state;    }}/* * 判断是否选择了记录     */function validateIsSelect(allobj,items){    var state = allobj.checked;    if(items.length){    for(var i=0;i<items.length;i++){    if(items[i].checked) return true;    }    }else{    if(items.checked) return true;    }    return false;}

<INPUT TYPE="checkbox" NAME="all"  onclick="javascript:allselect(this, this.form.productids)">全选</td>

<input name="visible" type="button" class="frm_btn" onClick="javascript:actionEvent('visible')" value=" 操作 ">