[英]How to check drop-down values using JavaScript
我在Gridview中有一個下拉菜單和Textbox,因此我想單擊一下按鈕檢查以下內容:(1)首先檢查是否從下拉菜單中選擇NOTHING(下拉選項為YES,NO或NA)。 如果未選擇任何內容,則要顯示如下消息:“請從下拉列表中進行選擇”(2)如果下拉列表中的選擇為“否”且“文本框”為空白或空,則我想顯示消息上面寫着:“請提供評論”
第一個代碼檢查文本框是否為空白並且可以正常工作,第二個代碼檢查下拉菜單中是否未選擇任何內容,並且也可以正常工作,因此如何在這兩個代碼之間進行組合? 我要在單擊按鈕時執行這兩個代碼,現在它僅調用第一個代碼。 請幫忙。 謝謝。 這是我的代碼,用於檢查文本框是否為空:
<script type ="text/javascript">
function Validate() {
var flag = false;
var gridView = document.getElementById('<%= GridView1.ClientID %>');
for (var i = 1; i < gridView.rows.length; i++) {
var selects = gridView.rows[i].getElementsByTagName('select');
var areas = gridView.rows[i].getElementsByTagName('textarea');
if (selects != null && areas != null) {
if (areas[0].type == "textarea") {
var txtval = areas[0].value;
var selectval = selects[0].value;
if (selectval == "No" && (txtval == "" || txtval == null)) {
flag = false;
break;
}
else {
flag = true;
document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'visible';
}
}
}
}
if (!flag) {
alert('Please note that comments are required if you select "No" from the dropdown box. Thanks');
document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'hidden';
}
return flag;
}
</script>
這是檢查下拉菜單的代碼
<script type="text/javascript">
function validate_DD() {
var flag = true;
var dropdowns = new Array(); //Create array to hold all the dropdown lists.
var gridview = document.getElementById('<%=GridView1.ClientID%>'); //GridView1 is the id of ur gridview.
dropdowns = gridview.getElementsByTagName('Select'); //Get all dropdown lists contained in GridView1.
for (var i = 0; i < dropdowns.length; i++) {
if (dropdowns.item(i).value == 'Select') //If dropdown has no selected value
{
flag = false;
break; //break the loop as there is no need to check further.
}
}
if (!flag) {
alert('Please select either Yes, No or NA in each dropdown and click the Save button again. Thanks');
document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'hidden';
}
return flag;
}
</script>
嘗試這個:
<select id="ddlCars">
<option value="1">Honda</option>
<option value="2" selected="selected">Toyota</option>
<option value="3">BMW</option>
</select>
訪問下拉菜單:
To get the value:
var el = document.getElementById("ddlCars");
var val = el.options[el.selectedIndex].value; // val will be 2
To get the text:
var el = document.getElementById("ddlCars");
var car = el.options[el.selectedIndex].text; //car will be Toyota
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