Add onerror example #439
Add onerror example #439
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beaufortfrancois
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Let's wait for @reillyeon to review before merging. |
index.html
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| reader.scan().then(() => { | ||
| console.log("Scan started successfully."); | ||
| reader.onerror = event => { | ||
| console.log("Error! Cannot read data from NFC tag."); |
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The log message below says "try again" but this case is really the one were retrying makes sense (tell the user to hold their device against the tag for longer) whereas an error below indicates a more fatal issue.
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The onerror event is raised only for IOException and FormatException, not TagLostException. I believe* this means holding device longer won't change anything. Both are fatal errors.
Do you want to me remove "try again" to make it clearer?
| Throws | Reason |
|---|---|
| TagLostException | if the tag leaves the field |
| IOException | if there is an I/O failure, or the operation is canceled |
| FormatException | if the NDEF Message on the tag is malformed |
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Interesting. Do you think we should fire an event on TagLostException? That seems like the most likely and most actionable error that a site could encounter.
Given the current behavior I would word the error as, "Error! Cannot read data from the NFC tag. Try a different one?"
My goal is for this example code to demonstrate to developers what parts of their UI should be responding to different events, and how. This also gives us a good opportunity to test whether or not developers will be able to easily code against these potential errors.
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I don't think TagLostExceptionprovides that much value as users will try again if they see app is not reacting, while IOException and FormatException are more "It's over" errors. They're nothing users can do about it as they use wrong formatted tags, and website will only show them something like "Sorry! This tag is not compatible with this application".
I'll update my example with your error message.
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See c5109bc
This PR addresses comment posted by @reillyeon in #432 (comment)
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