简单的Javascript下拉框启用问题

时间:2011-05-19 16:47:43

标签: javascript html drop-down-menu

怀疑我做了一些愚蠢的事情,但我现在看不到木头的树木了。另一双眼睛可能会立即解决这个问题。

    <script>
        function ChkStatus1() {
            if (document.frm1.LabelReq_1.value = "1") {
                document.frm1.LabelReason_1[0].selected = true;
                document.frm1.LabelReason_1.disabled = true;
            }
            if(document.frm1.LabelReq_1.value = "0") {
                document.frm1.LabelReason_1.disabled = false;
            }
        }
</script>

                    <Select name="LabelReq_1" onchange="ChkStatus1();">
                        <option value="1">Yes</option>
                        <option value="0">No</option>
                    </Select>
                    <Select name="LabelReason_1" disabled="disabled">
                        <option>[Please select why not required]</option>
                        <option>Reason 1</option>
                        <option>Reason 2</option>
                        <option>Reason 3</option>
                        <option>Reason 4</option>
                        <option>Reason 5</option>
                    </Select>

当我选择No时,一切都按照我的预期进行,但是当我选择'Yes'时它会执行'LabelReason_1 [0] .selected = true;'但随后不会更改LabelReq_1组合框。

谁能看到我哪里出错了?

提前致谢

格雷姆

2 个答案:

答案 0 :(得分:4)

将if语句中的=更改为==
=赋值,==表示相等

<script>
        function ChkStatus1() {
            if (document.frm1.LabelReq_1.value == "1") {
                document.frm1.LabelReason_1[0].selected = true;
                document.frm1.LabelReason_1.disabled = true;
            }
            if(document.frm1.LabelReq_1.value == "0") {
                document.frm1.LabelReason_1.disabled = false;
            }
        }
</script>

答案 1 :(得分:1)

您需要使用==或===而不是=:

<script>
        function ChkStatus1() {
            if (document.frm1.LabelReq_1.value == "1") {
                document.frm1.LabelReason_1[0].selected = true;
                document.frm1.LabelReason_1.disabled = true;
            }
            if(document.frm1.LabelReq_1.value == "0") {
                document.frm1.LabelReason_1.disabled = false;
            }
        }
</script>