如何使用OnChange将数据从javascript传输到php

Question

im试图从DropDown菜单中获取一些数据，当它更改为在秒级DropDown中进行查询时，我想使用该值，但直到现在，我还无法使用javascript将该值发送到我的php。

我使用这个代码：

<script type="text/javascript" language="javaScript">
function flow() {

var x = document.getElementById("txt_maq").value;
document.getElementById("demo").innerHTML = x;

var maq = document.getElementById('txt_maq').value;
var cat = document.getElementById('txt_catmaterial').value;
if (maq != "")
{
document.getElementById('txt_catmaterial').disabled=false;
}
if (cat == "")
{
document.getElementById('txt_material').disabled=true;
}
if (cat != "")
{
document.getElementById('txt_material').disabled=false;
}


}
</script>

<div class="col-2">
<div class="input-group">
<label class="label">Maq. Destino</label>
<div class="rs-select2 js-select-simple select--no-search">
<select id="txt_maq" name="txt_maq" onchange="flow()">
<option value="">Selecione</option>
<option value="E02">E02</option>
<option value="E03">E03</option>
<option value="E04">E04</option>
<option value="E05">E05</option>
<option value="E06">E06</option>
<option value="E07">E07</option>
<option value="E08">E08</option>
<option value="E04/E07">E04/E07</option>
<option value="E04/E08">E04/E08</option>
<option value="E03/E04">E03/E04</option>
<option value="E03/E07">E03/E07</option>
<option value="E04/E07/E08">E04/E07/E08</option>
<option value="E03/E07/E08">E03/E07/E08</option>
<option value="E07/E08">E07/E08</option>
<option value="E09">E09</option>
</select>
<div class="select-dropdown"></div>
</div>    
</div>
</div>
</div>
<div class="row row-space">
<div class="col-2">
<div class="input-group">
<label class="label">Cat. Material</label>
<div class="rs-select2 js-select-simple select--no-search">
<select id="txt_catmaterial" disabled="true" name="txt_catmaterial" onchange="flow()">
<option value=""></option>
<?php
$maquina = $_POST['txt_maquina'];
$type_te = "";

if ($maquina == "E09"){
$type_te= "ET";
} else {
$type_te= "EP";
}

echo $type_te;
$selecione = "";
$consulta = "SELECT Cat_Material FROM cat_mat where TE = '".$type_te."' "; //código SQL


$resultado = mysqli_query($ligacao,$consulta);
while ($listar = mysqli_fetch_array($resultado)){
$catmat = $listar['Cat_Material'];

echo "<option value=".$catmat.">$catmat</option>";
}
?>                                          
</select>   

<div class="select-dropdown"></div>
</div>        
</div>
</div>
</div>

如果txt_maq是E09，我所要做的就是生成一个If，这样我就可以在txt_catmaterial中进行查询，但值不是来自javascript。

Answer 1

使用Ajax将数据从Javascript发送到PHP

function testEndpoint(){
$.ajax({
url: "https://path/to/your-php-script.php",
type: "POST",
crossDomain: true,
data: {"txt_maq": $("#txt_maq").val()},
dataType: "json",
error: function(xhr, status, error){
console.log("Error: " + error);
},
success: function(result, status, xhr){
console.log(result);
}
});
}
testEndpoint();

在您的PHP脚本your-php-script.php您可以使用txt_maq作为POST变量：

$useTxtMag = $_POST['txt_maq'];

Answer 2

Ajax应该在包含jQuery之后使用，或者您可以简单地将jQuery包含在头部元素中