What does the "blur" input do in the emailInput.addEventListener.
What do the capture strings do?(reformatting phone#)

Question

Following along with the video, I am insure what blur means:

emailInput.addEventListener("blur", e => {
  e.target.value = formatTelephone(e.target.value)
});

and I also don't know when you would use the capture groups- is it only used when grouping something together?

return text.replace(regex, '($1) $(2-$3)')

Steven Parker · Accepted Answer

"Blur" is the opposite of "focus".  It's a bit of a funny name, but it's short.  You might think of it as "losing-focus", which is perhaps a better way to describe when it happens.  For more details, see this MDN page (https://developer.mozilla.org/en-US/docs/Web/API/Element/blur_event).
And capture groups are useful when you want to use pieces of the matched string when building new strings (possibly for replacements).   This should become more clear with additional examples, which you should see in the lessons ahead.  Meanwhile, here's an MDN page (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Groups_and_Ranges) that provides a couple of examples you can play with.

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Stephanie De La Melena

Stephanie De La Melena

What does the "blur" input do in the emailInput.addEventListener. What do the capture strings do?(reformatting phone#)

1 Answer

Steven Parker

Steven Parker