javascript - 我如何判断复选框是否已选中？

Question

我需要能够判断是否选中了复选框以进行一些基本验证。问题:我无权访问生成此内容的 PHP。没有添加类，或者大多数表单都有的基本的checked=checked。定位复选框的最简单方法是什么？

http://www.inpresence.in/event-registration?ee=4

编辑:吓坏了!这是代码，我只需要定位复选框，其他一切都正常。 jquery 的 :checked 方法在复选框中使用了checked=checked，但该复选框不存在。

   $(document).ready(function(){
    //when the submit button is clicked...
    $("input.btn_event_form_submit").click(function(){

    //find the value of the drop down with one evening or four evenings
    var priceOption = $("#price_option-4").val();

    //match a string ending with "one evening" as the first numbers will be randomly generated by php
    var oneEvening = /^\d{2}\|One Evening$/.test(priceOption);

    //match a string ending with "four evenings" as the first numbers will be randomly generated by php
    var fourEvenings = /^\d{2}\|Four Evenings$/.test(priceOption);

    //HOW DO I GET THE CHECKED BOXES?!
    var checkedBoxCount = $('#dates-1351733097 .valid').is(':checked').length;

    //if one evening is selected make sure the checked boxes count does in fact equal one
    if(oneEvening && checkedBoxCount != 1){
        //if it doesn't alert the user and return false
        alert('You must select one date');
        return false;
    }

    //if one evening isn't selected, four is. make sure the count does indeed in 4
    else if (fourEvenings && checkedBoxCount != 4){
        //if it doesnt alert the user and return to the form
        alert('You must select four dates');
        return false;
    }

    //else, everything checks out!
    else {
        return;
    }

});
});

Answer 1

使用此 JavaScript 代码，您可以检查复选框是否已选中:

var isChecked = document.getElementById("my-checkbox").checked;

或者使用 jQuery:

var isChecked = $('#my-checkbox').is(':checked');

编辑:尝试一下并告诉我它是否有效:

var checkedBoxCount = $('#dates-1351733097 .valid:checked').length;