php - 如何将我的 php 变量传递给 javascript

Question

我有一个动态下拉列表。填充第二个下拉列表。当我使用一个 php 变量进行测试时更改选择时，我的 javascript 没有使用我的变量。我是新手

Javascript:

<script type="text/javascript">
function populate(s1,s2){
var s1 = document.getElementById(s1);
var s2 = document.getElementById(s2);
s2.innerHTML = "";
if(s1.value=="<?php echo $car; ?>"){
var optionArray=[" ","camero Camaro","convette Convette"];
} else
if(s1.value=="Dodge"){
var optionArray=[" ","avanger Avanger","challenger Challenger"];
} else if(s1.value=="Ford"){
var optionArray=[" ","mustang Mustang","fiesta Fiesta"];
}
for (var option in optionArray){
var pair = optionArray[option].split(" ");
var newOption = document.createElement("option");
newOption.value = pair[0];
newOption.innerHTML = pair[1];
s2.options.add(newOption);
}
}
</script>

PHP 文件:

<select name="slct1" id="slct1" onchange="populate(this.id,'slct2')">

<option value=""></option>
<option value="<?php $car = 'Chevy';echo $car; ?>">Chevy</option>
<option value="Dodge">Dodge</option>
<option value="Ford">Ford</option>
</select>
<hr />
<select id="slct2" name="slct2">
</select>
<hr />

Answer 1

是因为你赋值了一个变量<?php $car = 'Chevy'; ?>

你需要打印它<?php echo 'Chevy'; ?>或 <?php echo $car; ?>