add javascript ajax example

examples/javascript/js_example/views.py

@@ -0,0 +1,16 @@
+from flask import jsonify, render_template, request
+
+from js_example import app
+
+
+@app.route('/', defaults={'js': 'plain'})
+@app.route('/<any(plain, jquery, fetch):js>')
+def index(js):
+    return render_template('{0}.html'.format(js), js=js)
+
+
+@app.route('/add', methods=['POST'])
+def add():
+    a = request.form.get('a', 0, type=float)
+    b = request.form.get('b', 0, type=float)
+    return jsonify(result=a + b)