There is some javascript code that

• marks fields as changed

when they are focussed and then blurred, whether or not there was an actual change.

On submitting, there is more javascript code that

• disables all fields not marked as changed

before submitting the values.

There is still more javascript code that, in the paraphrased words of the original author,

• awkwardly detects changes to sample data

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The problem with the javascript code above is that it is hacky and the solutions are brittle. For example

• marking the field as changed on blur rather than actually comparing the values
• not submitting original values making it impossible to compare values on backend
• detecting changes by setting a flag: the user can very easily restore the value to original before submitting, making the set flag indicate the wrong thing

I think, in general, we need to instead set the values based on comparisons:

• Submit both the old values and new values
• Compare old value and new value
• If different, add field/key to "update list"
• If not, don't add the field/key at all
• Use final "update list" to build the dictionary or data object to use for the update