在Ajax成功回調內的forloop中未定義response [i]

Question

錯誤

TypeError: response[i] is undefined


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

數組

[{"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成功回電

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>");

    }
}

為什么此響應[i]未定義？

Answer 1

它應該是i < size因為數組索引是從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>");

}

因此，當i == size時， response[i]的值將不確定

Answer 2

這樣的事情會起作用

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

更改為：

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>");

    }
}

如果您僅采用已過濾值的大小，則可以使用已過濾數組來避免null或未定義的值。 我也<大小。