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Learn ESP Course, Module 4, Unit 11 – Asynchronous Web Server: Improper use of graphic symbol in original code

Q&A Forum › Learn ESP Course, Module 4, Unit 11 – Asynchronous Web Server: Improper use of graphic symbol in original code
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Steve Lehr asked 4 years ago
The original code worked fine as advertised, but when I swapped the paragraph blocks, the resulting display was a contorted version of the original.
The modified code is linked here:
The problem appears to be the use of the percent symbol (%) in the units line of the humidity paragraph block.  This was meant to be used as a graphic symbol to display the units for humidity.  I believe the percent symbol is a special character used to delimit such things as the placeholder definitions and just inserting it between the brackets >%< causes problems downstream when the symbols are later used in the same body block.  Instead, you should use the graphic code for the percent symbol (&#37 or &percent) in the units block.  The following code snippet produces the desired result.
As shown here:
Any other thoughts on this?
3 Answers
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Sara Santos Staff answered 4 years ago

Hi Steve.
You are right.
To prevent issues with the % sign, we should use the HTML entity as you said.
We need to change that in the next ebook update.
Thanks for your comment.
Regards,
Sara

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Steve Lehr answered 4 years ago

Having experimented with this projected I learned that the sensor values are only written to the serial monitor when a browser is actively connected to the ESP32 web server.  I suppose that’s because the commands to read the sensors are initiated by the Javacode that has been uploaded to the browser.  This would make asynchronous unsuitable for a system intended to take regular measurements independent of a browser.  

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Sara Santos Staff answered 4 years ago

Hi Steve.
In that specific example, getting the readings is triggered by the browser. It makes a request to the ESP32, it gets the readings and sends them back to the browser.
If you want to get readings independent of a browser, you need to set up your code in a different way.
Regards,
Sara