Created
August 11, 2022 17:47
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update periodically text in browser using ajax
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| from flask import Flask, render_template_string | |
| import time | |
| app = Flask(__name__) | |
| @app.route('/') | |
| def index(): | |
| return render_template_string('''<p>This is the current value: <span id="latest_value"></span></p> | |
| <script> | |
| var latest = document.getElementById('latest_value'); | |
| var xhr = new XMLHttpRequest(); | |
| xhr.open('GET', '{{ url_for('stream') }}'); | |
| xhr.onreadystatechange = function() { | |
| var all_lines = xhr.responseText.split('\\n'); | |
| last_line = all_lines.length - 2 | |
| latest.textContent = all_lines[last_line] | |
| if (xhr.readyState == XMLHttpRequest.DONE) { | |
| /*alert("The End of Stream");*/ | |
| latest.textContent = "The End of Stream" | |
| } | |
| } | |
| xhr.send(); | |
| </script>''') | |
| @app.route('/stream_time') | |
| def stream(): | |
| def generate(): | |
| while True: | |
| current_time = time.strftime("%H:%M:%S\n") | |
| print(current_time) | |
| yield current_time | |
| time.sleep(1) | |
| return app.response_class(generate(), mimetype='text/plain') | |
| app.run() |
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Now in JavaScript you have to use xhr.onreadystatechange to assign function which will update text on page when it gets new data from server
https://stackoverflow.com/questions/61398680/updating-streamed-data-from-flask-in-real-time