如何从select标记中获取和输出值

// 获取选中的值
var selectedValue = $('#selectId').val();

// 输出选中的值
console.log(selectedValue);

<!-- HTML表单 -->
<form method="post" action="process.php">
  <select name="selectName" id="selectId">
    <option value="value1">Option 1</option>
    <option value="value2">Option 2</option>
    <option value="value3">Option 3</option>
  </select>
  <input type="submit" value="Submit">
</form>

<!-- process.php -->
<?php
// 获取选中的值
$selectedValue = $_POST['selectName'];

// 输出选中的值
echo $selectedValue;
?>

# views.py
from django.shortcuts import render

def process_form(request):
    if request.method == 'POST':
        # 获取选中的值
        selected_value = request.POST.get('selectName')

        # 输出选中的值
        print(selected_value)

    return render(request, 'form.html')

<!-- form.html -->
<form method="post" action="{% url 'process_form' %}">
  {% csrf_token %}
  <select name="selectName" id="selectId">
    <option value="value1">Option 1</option>
    <option value="value2">Option 2</option>
    <option value="value3">Option 3</option>
  </select>
  <input type="submit" value="Submit">
</form>