<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">

<title>javascript checkbox全选 反选  全不选</title>

<meta name="description" content="">

<meta name="keywords" content="">

<link href="" rel="stylesheet">

</head>

<body>

    <form action="">

        <p><input type="checkbox"></p>

        <p><input type="checkbox"></p>

        <p><input type="checkbox"></p>

        <p><input type="checkbox"></p>

        <p><input type="checkbox"></p>

        <p><input type="checkbox"></p>

        </br>

        <input type="button" id="a_xuan" value="全选" onclick="all_xuan()">

        <input type="button" id="a_n_xuan" value="反选" onclick="fan_xuan()">

        <input type="button" id="f_xuan" value="全不选" onclick="all_no_xuan()">

    </form>

</body>

<script>

//全选

function all_xuan()

{

    var all_xuan=document.getElementById('a_xuan');

    if(all_xuan!='')

    {

        var input_c=document.getElementsByTagName('input');

        for(var i=0;i<input_c.length;i++)

        {

            input_c[i].checked="true";

        }

    }

}

//全不选

function all_no_xuan()

{

    var all_xuan=document.getElementById('f_xuan');

    if(all_xuan!='')

    {

        var input_c=document.getElementsByTagName('input');

        for(var i=0;i<input_c.length;i++)

        {

            input_c[i].checked="";

        }

    }

}

//反选

function fan_xuan()

{

    var all_xuan=document.getElementById('a_n_xuan');

    if(all_xuan!='')

    {

        var input_c=document.getElementsByTagName('input');

        for(var i=0;i<input_c.length-1;i++)

        {

            if(input_c[i].checked)

            {

                input_c[i].checked="";

            }else

            {

                input_c[i].checked="true";

            }

        }

    }

}

</script>

</html>