Javascript 强制更改为特定值
我有一个HTML代码和Javascript,看起来像这样:Javascript 强制更改为特定值,javascript,php,html,Javascript,Php,Html,我有一个HTML代码和Javascript,看起来像这样: <td>Item Category</td> <td> <select id="item_category_selection" onchange="item_category(value)"> <option>Select</option>
<td>Item Category</td>
<td>
<select id="item_category_selection" onchange="item_category(value)">
<option>Select</option>
<?php
$type_result = mysql_query("SELECT DISTINCT ItemCategory FROM ".$dmt_objects." ORDER BY ItemCategory ASC ");
while($type_array = mysql_fetch_array($type_result)){
if($type_array['ItemCategory'] !== "N/A" && $type_array['ItemCategory'] !== "Item"){
echo "<option>".$type_array['ItemCategory']."</option>";
}
}
?>
</select>
</td>
这将产生一个包含不同选项的列表,但是这些选项没有分配任何值。看起来是这样的:
<select id="item_category_selection" onchange="item_category(value)">
<option>Select</option>
<option>Alt 1</option>
<option>Alt 2</option>
function item_category(val){
selected_item_category = $("#item_category_selection").val();
document.getElementById("sel_target").innerHTML = "";
$.ajax({
type: "POST",
url: "find_objects.php",
data: {selected_item_category:selected_item_category, selected_project:selected_project},
dataType: 'json',
success: function(data){
$('#sel_target').append("<option value='Select value' >Select Value</option>");
$('#sel_target').append("<option value='PAINT ALL' >Show All</option>");
var array_length = data.length;
for(var i = 0; i < array_length; i++){
var ItemName = data[i].ItemName;
var DatabaseID = data[i].DatabaseID;
$('#sel_target').append("<option value='"+DatabaseID+"' >" + ItemName + "</option>");
}
return false;
}
});
}
调用的函数如下所示:
<select id="item_category_selection" onchange="item_category(value)">
<option>Select</option>
<option>Alt 1</option>
<option>Alt 2</option>
function item_category(val){
selected_item_category = $("#item_category_selection").val();
document.getElementById("sel_target").innerHTML = "";
$.ajax({
type: "POST",
url: "find_objects.php",
data: {selected_item_category:selected_item_category, selected_project:selected_project},
dataType: 'json',
success: function(data){
$('#sel_target').append("<option value='Select value' >Select Value</option>");
$('#sel_target').append("<option value='PAINT ALL' >Show All</option>");
var array_length = data.length;
for(var i = 0; i < array_length; i++){
var ItemName = data[i].ItemName;
var DatabaseID = data[i].DatabaseID;
$('#sel_target').append("<option value='"+DatabaseID+"' >" + ItemName + "</option>");
}
return false;
}
});
}
现在,我想强制它使用一个选项,并调用函数。我该怎么做?当您单击其他按钮时,我希望Itemcategory更改为特定的类别
var setValue = 'Alt 1';
$('#item_category_selection')
.val(setValue) // set the value of the <select>
.change() // call the 'onchange' function
;
选择
备选案文1
备选案文2
首先,为每个选项赋予值,并将onchange=item\u categoryvalue更改为onchange=item\u categorythis.values。其次,您不需要发送带有参数的值,因为您没有使用它。您可以从selected_item_category=$item_category_selection.val;好的,但是如何手动设置项目类别?类似于item\u category\u selection=Alt 1