使用下拉菜单重置特定于Javascript的字段

需要一些javascript方面的帮助。不太熟悉javascript。我想知道是否有人对此有所了解

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

工作流程/概述：
4个字段
用户在字段2-4中输入数据
用户从字段1的下拉菜单中选择重置

字段重置为默认值
-字段2重置>请选择
-字段3重置>空白
字段不会重置
-字段4不休息>保留输入的值

谢谢你的帮助

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

代码

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

字段1*：
重置
1.
2.
3.


字段2
请选择
1.
2.
3.


字段3


字段4

您应该阅读一些关于javascript的知识，因为这是最基本的知识之一（请查看jquery）

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

主要是为了从javascript访问项目，您可以这样做：

var element=document.getElementById（'select2'）

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

现在，当您有元素“element”时，您可以在其中输入值。 element.value=“请选择”

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

最后的代码是：

</script>

    <form name="testform" action="" method="get">
        <fieldset>
            <label>Field 1<font color="red">*</font>:</label>
            <select name="select1" id="select1">
                <option value="Reset">Reset</option>
                <option value="1" selected>1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            <br/>
            <label>Field 2</label>
            <select name="select2" id="select2">
                <option value="Please select">Please select</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
            </select>

            </br>
            <label>Field 3</label>
            <input type="text" name="text1" size="100"/>

            </br>
            <label>Field 4</label>
            <input type="text" name="text2" size="100"/>
        </fieldset>

    </form>
</body></html>

<select name="select1" id="select1" onchange="maybeReset()">

function maybeReset(){
element1  = document.getElementById('select1');

if (element1.value == "Reset")
{
var element  = document.getElementById('select2');
element.value = "Please select";

...
}

} 

函数maybeReset（）{
element1=document.getElementById（'select1'）；
如果（element1.value==“重置”）
{
var元素=document.getElementById（'select2'）；
element.value=“请选择”；
...
}
}