Trying to find out if a string with it's characters separated by commas contains only digits

Question

If the string contains any characters besides a number or the comma that separates it from the other character the function should return "invalid input", if they're all numbers it should output "great job"

a,4,3,@ = "invalid input"...

1,4,6,5 = "great job" <===returned from function

I'm trying to learn about regex but if you could do it using another method that's ok. I'm interested in how you would go about solving it. I couldn't find an answer online my self. I searched. I know that d(regex) is for digits but I just don't now how to apply it for this case.

Answer 1

You can use a simple regular expression to check that the string contains only comma separated numbers:

/^(\d+,)*\d+$/.test(s)

And use it like:

['1,2,3','123,5,223','1@32','12','12,',',23',','].forEach(function(s) {
  document.write('<br>' + s + ' : ' + (/^(\d+,)*\d+$/.test(s)? 'great job' : 'invalid input'));
});

This assumes that numbers can have any number of digits and that commas are only allowed between numbers; not at the start, end or consecutively.

Answer 2

You can split a string into an array on a character using String.split(char), for example:

'1,4,6,5'.split(',');
> [1, 4, 6, 5]

You could then use a regex to check if the character is a number and a reducer to validate.

function valid(c) {
   //using regex, return true if the character is valid, false if not
   // or something like
   return !Number.isNaN(+c);
}

'1,4,6,5'.split(',').reduce(function(acc, x) {
     if valid(x) {
        return acc;
     } else {
        return false;
     }
 }, true);

that should give you a boolean that you can map to your desired output string. reduce works sort of like a loop, it passes an accumulated value and each element of the array one at a time, with the inital value given as at the part here '}, true);' so as long as the regex returns true, we keep returning the same acc value, but if we get an invalid regex we switch the accumulator to false. note that because we don't change the accumulator value on valid inputs, we don't have to worry about it suddenly reventing back to a 'valid' status.

Answer 3

You can use the Array.prototype.every() method

return str.split(',').every(function(val) {
    return parseInt(val) == val; // or any of the many other ways to check if a string is a number
});

Answer 4

Helpful links:

Check whether an input string contains number

Check if string contains only digits

I threw this together, hopefully it helps! It is a working function, like you asked.

function isOnlyNumsAndCommas(str) {
  for (var i = 2; i <= str.length + 2; i += 2) {
    var val = str.substring(i - 2, i - 1);
    var isnum = val.match(/\d+/g);
    if (!isnum) {
      return ('invalid input');
      break;
    }
  }
  return('great job');
}

alert(isOnlyNumsAndCommas("@,4,3,3"));

For a non 'for loop' function!

function isOnlyNumsAndCommas(str) {
  if (str.match(/[^\d|,]/) === null) {
    return('great job');
  } else {
    return('invalid input');
  }
}

alert(isOnlyNumsAndCommas("a,4,3,@"));

Answer 5

var hasCommaSeparatedDigits = function(str){
    var strArr = str.split(",");
    var res = strArr.length ? "Great job!" : "Invalid Input";
    for(var i in strArr){
     var ch = strArr[i];
        if(isNaN(ch)){
            res = "Invalid Input";
            break;
        }
    }
    
    return res;
}

console.log(hasCommaSeparatedDigits("1,2,3,4"));
console.log(hasCommaSeparatedDigits("1,a,3,4"));

Answer 6

There is no need to split the string, loop and check for validity of each part. Just do a regex check for presence of a non-digit excluding the comma (this assumes that a comma can occur anywhere)

try:

var str = "1,2,3,";
if(str.match(/[^\d|,]/) == null)
 alert("great job");
else
 alert("err");

Answer 7

function isValid(str){
    var res = str.split(',').every(function(item){ 
        return !isNaN(item) ? true : false;
  });
return res ? "great job" : "invalid input";
}
console.log(isValid("1,2,4,5,@"))