前六个手机号码不应该相同[关闭]

I need to find if the mobile number contain the first 6 digit same or not.

the last five numbers could be the same.

But i need to check if only the first 6 number are same

say for example if have a mobile number, 8999999589 then there should not be any consecutive 6 number at any point.

Dumb and fast way, use regexes :

const falseNumber = '66666655555';
const trueNumber = '12345655555';

const isFalse = function (num) {
  const regex = new RegExp('^(' + new Array(10)
    .fill(0)
    .map((v, i) => new Array(6).join(i))
    .join('|') + ')');
  return !regex.exec(num);
}

console.log(falseNumber + ' is ' + isFalse(falseNumber));
console.log(trueNumber + ' is ' + isFalse(trueNumber));

You can even shorten it : if you can replace the six same first numbers, then it's false.

const falseNumber = '66666655555';
const trueNumber = '12345655555';

function isFalse(num) {
  return num.replace(/^(\d)\1{5}/, '').length !== num.length;
}

console.log(falseNumber + ' is ' + isFalse(falseNumber));
console.log(trueNumber + ' is ' + isFalse(trueNumber));

</div>

You can do something like this:

// Your array of numbers, I supposed you want to understand if
// there are 6 numbers repeated after the international prefix
// if you want something else you can easily edit indexes
const phoneNumbers = [
    '+44111111654',
    '+44111235646',
    '+44222222456',
    '+44123456789',
];

// A first cycle where we scan all the numbers in phone numbers
for (let i = 0; i < phoneNumbers.length; i++) {
    // we split the number in single chars array
    const numbers = phoneNumbers[i].split('');
    console.log(phoneNumbers[i]);
    let counter = 1;
    // A second cycle where we compair the current index element with the previous one
    for (let j = 0; j < numbers.length; j++) {
        // if the index is between 2 and 9 (+44 ->111111<- 456)
        if (j > 2 && j < 9) {
            // if the number in current position is equal to the one
            // in previous position we increment counter
            if (numbers[j] === numbers[j-1]) {
                counter++;
            }
        }
    };
    console.log(counter);
    // if counter is equal to 6, we have an invalid number (as you specified)
    if (counter === 6) {
        console.log('NOT VALID NUMBER AT INDEX: ', i);
    }
    console.log('-------');
};

OUTPUT:

+44111111654
6
NOT VALID NUMBER AT INDEX:  0
-------
+44111235646
3
-------
+44222222456
6
NOT VALID NUMBER AT INDEX:  2
-------
+44123456789
1
-------

First, get the first number to compare:

firstNumber = mobileNumberStr[0];

and then check if the following is true

mobileNumberStr.substr(0, 6) === firstNumber.repeat(6)

Summary:

If you want a one liner function:

const isNumberValid = mobileNumber => mobileNumber.substr(0, 6) === mobileNumber[0].repeat(6)