Javascript最大选中输入类型数复选框

var inputs = document.getElementsByTagName("input");
var numSelected = 0;
var current;

for (var i=inputs.length;i--;) {
    current = inputs[i];

    if (current.type.toLowerCase() == "checkbox" && current.checked && current.name.indexOf("pdf") == 0) {
        current++;
    };
};

if (current > 5) {
    alert("You've got " + current + " selected! :(");
}

如果您碰巧使用了jQuery,那就很简单了

var selectedPdfCheckboxes = $('input:checkbox[name^=pdf]');

if (selectedPdfCheckboxes.length > 5) {
    alert("You've got " + selectedPdfCheckboxes.length + " selected! :(");
}

我使用的jQuery选择器( ^= )读作“start with”,所以不需要*等价物。

jQuery代码将在任何地方执行,但是必须在 document.ready()

$(document).ready(function () {
    $("#aForm").bind('submit', function (e) {
        var selectedPdfCheckboxes = $('input:checkbox[name^=pdf]');

        if (selectedPdfCheckboxes.length > 5) {
            alert("You've got " + selectedPdfCheckboxes.length + " selected! :(");

            e.preventDefault();        
        }
    });
});