sourcecode

// test.vue
<template>
  <h1> Test Render</h1>
</template>

<script>
export default {

}
</script>

<style scoped>

</style>

// app.js
import Vue from 'vue'
import test from './component/test.vue'

new Vue({
    el: '#app',
    render: h => h(test)
})

// index.html
<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Vue Testing</title>

    <!-- Javascript -->
    <script src="https://cdn.jsdelivr.net/npm/vue"></script>
</head>

<body>
    <div id="app">
    </div>

    <script src="(( url_for('static', filename='js/app.js') ))"></script>
</body>

</html>

// app.py
from flask import Flask, render_template
from flask_cors import CORS

class CustomFlask(Flask):
    jinja_options = Flask.jinja_options.copy()
    jinja_options.update(dict(
      block_start_string='{%',
      block_end_string='%}',
      variable_start_string='((',
      variable_end_string='))',
      comment_start_string='{#',
      comment_end_string='#}',
))

app = CustomFlask(__name__)
CORS(app)

@app.route('/')
def index():
    return render_template('index.html')

if __name__ == '__main__':
    app.run(debug=True)