数字字符串转成数字
function strNumberToNumber (s) {
let i = 0
let res = 0
while (i < s.length && s[i] >= '0' && s[i] <= '9') {// ans = ans * 10 + (s[i++] - '0');
let cur = +s[i] // 字符串转整数
res = res * 10 + cur
i++
}
return res
}
const s = '4193'
const result = strNumberToNumber(s)
console.log('result', result) //4193