node js, give a string composed of numbers, for example, "8910151821", how to get the number of numbers between 3 and 20 in this string, the result should be: 8, 9, 10, 10, 15, 18, a total of 5 numbers, 21 of which does not count, how can it be realized? Thank you
let compare = (d) => {
return d > 3 && d < 20
}
'8910151821'.split('').map((d, i, arr) => {
d = +d;
if (i > 1) {
let comD = arr[i - 1] * 10 + d;
return compare(comD) ? comD : null
} else if (compare(d)) {
return d;
}
}).filter(d => d);const countNum = s => [...s].reduce((res, val) => {
switch (true) {
case !+val && res[2]:
console.log('2' + val)
res[0]PP
res[2] = false
break
case +val > 2 && !res[1]:
console.log(val)
res[0]PP
break
case +val && +val < 3 && !res[1]:
res[val] = true
break
case res[1]:
console.log('1' + val)
res[0]PP
res[1] = false
break
default:
[res[1], res[2]] = [false, false]
break
}
return res
}, [0, false, false])[0]
countNum('8910151821')is that what it means?
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