你如何检查一个复选框是否被选中[重复]答案

【问题标题】：How do you check whether a check box is checked or not [duplicate]你如何检查一个复选框是否被选中[重复]
【发布时间】：2015-08-30 10:32:21
【问题描述】：

我正在申请积分。我将如何检查复选框是否被选中，如果它是如何让它添加 10，如果它没有被选中，我希望它什么都不做。这是JavaScript。 JS

if (localStorage.getItem("studentList") === null) {
    localStorage.setItem("studentList", JSON.stringify([]));
}

studentList = JSON.parse(localStorage.getItem("studentList"));

function save() {
    newStudent = {
        "firstname": document.getElementById('sFirstName').value,
        "lastname": document.getElementById('sLastName').value,
        "studentnumber": document.getElementById('sNumber').value,
        "points": document.getElementById('sPoints').value
    };  

    studentList.push(newStudent);
    localStorage.setItem("studentList", JSON.stringify(studentList));
};
table = document.getElementById("attendance");
for (i = 0; i < studentList.length; i++) {
    row = table.insertRow(i + 1);
    cell1 = row.insertCell(0);
    cell2 = row.insertCell(1);
    cell3 = row.insertCell(2);
    cell4 = row.insertCell(3);
    cell5 = row.insertCell(4);

    cell1.innerHTML = studentList[i].firstname;
    cell2.innerHTML = studentList[i].lastname;
    cell3.innerHTML = studentList[i].studentnumber;
    cell4.innerHTML = studentList[i].points;
    cell5.innerHTML = "<input type=checkbox>";
}


function userName() { //this function takes values from the text box and stores them in objects

    var studentList = {
        studentNumber: document.getElementById("newUser").value + index,
        lastName: document.getElementById("newlName").value + index,
        firstName: document.getElementById("newfName").value + index

    };
}

这是一个 JSfiddle：https://jsfiddle.net/RandomRainbow7/Lm574foy/ 小提琴不会显示一个人，所以如果你想硬编码它，否则这里是另一个 html 页面。

<!DOCTYPE html> 
<head>
<!--<link href="style.css" rel="stylesheet" type="text/css">-->
<script src="function.js"></script>
</head>
<header>
    <nav>
        <img src="logo.jpg"><h1 id="titt">North Park Clubs</h1>
    <li>
        <a href="attendance.html">Attendance</a>
        <a href="addStudent.html">Add Student</a>
        </li>
    </nav>
</header> 
<body>
<h1>Add A Student</h1>
    <input type="text" id="sFirstName" placeholder="First Name"></input>
    <input type="text" id="sLastName" placeholder="Last Name"></input>
    <input type="text" id="sNumber" placeholder="Student Number"></input>
    <input type="text" id="sPoints" placeholder="Points"></input>
    <input type="button" id="checkbox"onclick="save()" value="Save"></input>

</body>

【问题讨论】：

标签： javascript html

【解决方案1】：

您可以将“缺席”的信息与学生的其他信息一起存储在 json 对象中：

将其存储在save() 函数中：

newStudent = {
    "firstname": document.getElementById('sFirstName').value,
    "lastname": document.getElementById('sLastName').value,
    "studentnumber": document.getElementById('sNumber').value,
    "points": document.getElementById('sPoints').value,

    "absent": document.getElementById('sAbsent').checked
};

在for-loop 中阅读表格：

cell1.innerHTML = studentList[i].firstname;
cell2.innerHTML = studentList[i].lastname;
cell3.innerHTML = studentList[i].studentnumber;
cell4.innerHTML = studentList[i].points;

cell5.innerHTML = "<input type=checkbox" + (studentList[i].absent === true) ? "checked>" : ">";
}

写在<h1>Add A Student</h1>下的HTML中：

<input type="checkbox" id="sAbsent"></input>

【讨论】：