How to validate cron-expression with giiven limit?

Question

I need to build a cron-validator. This is a cron expression,it means every 30 seconds.

*/30 * * * * *

The task is to show an error if the time is less than 30 seconds. Example: So if I write the following, which means, every 10 seconds,

*/10 * * * * *

It should show an error saying, "Please enter more than 30 seconds". Here is example function, expression is cron expression, limit is in miliseconds, So if I pass 30 second, it should validate 30 seconds.

function cronValidator(expression = '', limit = 30000){}

So far, I have tried this:

function cronValidator(expression = '', limit = 30000) {
  // filter the number of seconds from expression
  const [seconds] = expression.match(/(\d+)/);
  // convert seconds into miliseconds
  const milisecondsInExpression = seconds * 1000;

  if (milisecondsInExpression < limit) {
    console.error(`Please enter more than ${limit / 1000} seconds.`);
  } else {
    console.log('You are good to go.');
  }
}

const cronExp = '*/31 * * * * *';

cronValidator(cronExp, 40000);

but it is not working, cause:

The limit or expression can be minutes or hours. Not just seconds. It means normal regex is not enough.

There's only 5 time fields: minutes, hours, days, months, weekdays. — Barmar, Jul 13 '20 at 05:20
Please verify your cron expression whether it is valid or not. You can check it out here https://crontab.guru/ — Dinesh Nadimpalli, Jul 13 '20 at 05:24

score 0 · Answer 1 · answered Jul 13 '20 at 05:25

0

Split the input into whitespace-separated fields, and just validate the first field. And you should only check the frequency if it's in the form */#.

let fields = expression.split(/\s+/);
let seconds = fields[0];
let split_seconds = seconds.match(/^\*\/(\d+)$);
if (split_seconds) {
    let milliseconds = split_seconds[1] * 1000;
    if (milliseconds < limit) {
        console.error(`Please enter more than ${limit / 1000} seconds.`);
    }
}

answered Jul 13 '20 at 05:25

Barmar

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but limit can also be hour, day, minute.. not just milisecond. – Ashik Jul 13 '20 at 05:34
I thought you just wanted to limit the seconds. – Barmar Jul 13 '20 at 05:36
If they split the hours, that's more than 30 seconds, so it shouldn't be necessary to limit it. – Barmar Jul 13 '20 at 05:36

How to validate cron-expression with giiven limit?

1 Answers1