Question

错误

TypeError: response[i] is undefined


    ...box' class='selectedSubjects' name='selectedSubjects' />
</td><td class='selected...

数组

[{"S_Code":"BCS-CER-IS","S_Name":"Information Systems.","C_Code":"BCS-CER","S_Status":"Active"},
{"S_Code":"BCS-CER-SD","S_Name":"Software Development.","C_Code":"BCS-CER","S_Status":"Active"},
{"S_Code":"BCS-CER-TEC","S_Name":"Computer & Network Technology","C_Code":"BCS-CER","S_Status":"Active"}]

AJAX成功回电

success: function (response) {
    var size = response.filter(function (value) {
        return value !== undefined
    }).length;
    for (var i = 0; i <= size; i++) {
        $("#subjectsTable tr:last").after("<tr class='success' data-index=" + (i + 1) + "><td><input type='checkbox' class='selectedSubjects' name='selectedSubjects' /></td><td class='selectedSCode'>" + response[i].S_Code + "</td><td class='selectedSName'>" + response[i].S_Name + "</td></tr>");

    }
}

为什么这个回复[i]未定义？

Answer 1

它应该是i < size，因为数组索引是从0到length-1

for (var i = 0; i < size; i++) {
    $("#subjectsTable tr:last").after("<tr class='success' data-index=" + (i + 1) + "><td><input type='checkbox' class='selectedSubjects' name='selectedSubjects' /></td><td class='selectedSCode'>" + response[i].S_Code + "</td><td class='selectedSName'>" + response[i].S_Name + "</td></tr>");

}

所以当i == size response[i]的值未定义时

Answer 2

这样的事情会起作用

for (var i = 0; i <= (size - 1); i++) {
        $("#subjectsTable tr:last").after("<tr class='success' data-index=" + (i + 1) + "><td><input type='checkbox' class='selectedSubjects' name='selectedSubjects' /></td><td class='selectedSCode'>" + response[i].S_Code + "</td><td class='selectedSName'>" + response[i].S_Name + "</td></tr>");
    }

Answer 3

将其更改为：

success: function (response) {
    var filtered = response.filter(function (value) {
        return value !== undefined
    });
    var size = filtered.length;

    for (var i = 0; i < size; i++) {
        $("#subjectsTable tr:last").after("<tr class='success' data-index=" + (i + 1) + "><td><input type='checkbox' class='selectedSubjects' name='selectedSubjects' /></td><td class='selectedSCode'>" + filtered[i].S_Code + "</td><td class='selectedSName'>" + filtered[i].S_Name + "</td></tr>");

    }
}

如果仅使用过滤后的大小，则使用过滤后的数组来避免空值或未定义的值。我也是＆lt;大小。

响应[i]在ajax成功回调中的for循环中未定义

3 个答案: