FA-96572 / Phone number formatting / Member archive

As-you-type ten-digit formatter: overlong input is forced into the mask · case 02

Eleven national digits render as "(555) 012-34567".

Member previewVariant 2 · 3 implementations · 11 checks per implementation

Case contract

Input the digits typed so far. A leading 1 becomes the prefix "1 ". With more than ten remaining digits the raw input is returned. Up to 3 digits are shown bare; 4..6 as "(AAA) E.."; 7..10 as "(AAA) EEE-S...". The result is stripped of surrounding spaces.

Why this case matters

Input masks re-render on every keystroke; premature punctuation or a lost prefix makes the caret jump and corrupts what users type.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
too many digits after the prefix	`"1 (655) 012-34562"`	`"165501234562"`	Failed

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