moment().isValid returns true when the input is in integers

Question

Code:

  let modifiedValue = attribute_value;
  let isISOFormat = moment(new Date(attribute_value), moment.ISO_8601, true).isValid();
  if (isISOFormat) {
    modifiedValue = formatDateShortCustom(moment(attribute_value).toDate());
  }
  return modifiedValue;
};

In the code above, the attribute value can have

2021-09-29T18:30:00.000Z
080921

I want to make sure that when the attribute_value is in (1) format the code
modifiedValue = formatDateShortCustom(moment(attribute_value).toDate()); should execute.

However, this numerical string is also causing the isISOFormat as true hence navigating the formatDateShortCustom method, which I don't want?

Is there anything I am doing wrong?

user_7237224 · Answer

I'd suggest wrapping this in a function isISOFormat() and using this to decide whether your input is an ISO 8601 date string.

I'd also suggest passing the input directly to the moment() constructor, rather than creating a Date first:

let attribute_values = ['2021-09-28T11:45:00Z', new Date().toISOString(), 20, null, '28/09/2021', 'is this a date?'];

function testIsISOFormat() {
    for(let attribute_value of attribute_values) {
        console.log(`isISOFormat(${attribute_value}):`, isISOFormat(attribute_value));
    }
}

function isISOFormat(input) {
    return moment(input, moment.ISO_8601, true).isValid();
}

console.log('Testing isISOFormat:');
testIsISOFormat()

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user_5189811 · Answer

moment.ISO_8601 is undefined below version 2.7.0.

That's why moment attempts to parse the value regardless of your setting the strict parsing option. moment checks if the string matches known ISO 8601 formats.

I recommend passing the format as the second argument explicitly.

console.log(moment('2021-09-29T18:30:00.000Z', 'YYYY-MM-DDTHH:mm:ss.SSSZ', true).isValid());

console.log(moment('080921', 'YYYY-MM-DDTHH:mm:ss.SSSZ', true).isValid());

moment().isValid returns true when the input is in integers

2 Answers