Simple demo of program synthesis based on reading positive and negative examples. Generates regex solution that will properly validate input and reject negative examples.
Number matcher.
$ node index.js check examples/numbers.tsv
0 /^$/
5 /^\d+$/
[Solved] Generated regex: /^\d+$/Phone number matcher.
$ node index.js check examples/phone.tsv
...
13 /^\d+[-]\d+[-]\d{3}$/
11 /^\d+[-]\d+[-]\d{2}$/
10 /^\d+[-]\d+[-]\d{1}$/
9 /^\d+[-]\d+[-]\d{0}$/
14 /^\d+[-]\d{3}[-]\d+$/
[Solved] Generated regex: /^\d+[-]\d{3}[-]\d+$/