Question 49266 in Javascript Question posted in
A very good W3school tutorial can be found here.

Check that a string equals "X.X", where X is a 0-9 digit – Javascript

I am trying to verify that a string corresponds to this format "x.x" with x, a digit belonging to [0-9].

Right now, what I am doing is:

  • checking that the string is at least, and at most, made of 3 characters
  • checking that the string matches the regex [0-9.] (only digits and a dot)

So right now, I have:

      myString: Yup.string()
        .min(3, "Minimum 3 caractères: XXX.")
        .max(3, "Maximum 3 caractères: XXX.")
        .matches(/^[0-9]+$/, 'Doit contenir seulement des caractères numériques.')
        .nullable(),

Is there a way for me to:

  • check that myString[0] and myString[2] are digits
  • check that myString[1] is a dot
Tags:

3

Answers


  1. 0

    What about just using the matches and pass a regex that validates the list of requirements in one go?

    const number = string().matches(/d{3,}.d{3,}/).nullable();

number.validateSync("123.456") // pass
number.validateSync("12.456") // fail min
number.validateSync("123456") // fail no dot
number.validateSync("1236.4566") // pass

    Here d{3,} matches a number with min 3 digits long followed by a dot . followed by another d{3,}.

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  2. 0

    You can improve your code just using regex, like in your case:

    yup.string()
  .matches('^d{1}.d{1}$', 'Doit contenir seulement des caractères numériques.')
  .nullable()

    d validates whether first and last characters are digits with second character being a .

    Since you only need one number its d{1} before and after the dot.

    Edit:

    As @bobble bubble mentioned and after testing d{1} is actually redundant. In your case, the regex pattern is ^d.d$. You can use the above pattern if you want to increase the digit count.

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  3. 0

    Another way is to use /^[0-9][.][0-9]$/, which I think is easier to read. Here is an example with tests:

    const regex= /^[0-9][.][0-9]$/;

console.log(regex.test("4.3")); // true
console.log(regex.test("9.0")); // true

console.log(regex.test("91.0")); // false
console.log(regex.test("4e3")); // false
console.log(regex.test("abc")); // false

    With Yup, in your case, it would be:

    Yup.string()
  .matches(
    /^[0-9][.][0-9]$/,
    'It should be in the form of Digit + Period + Digit'
  )
  .nullable();

    Also, you can copy past the RegEx in regexr.com to get an explanation of each part of it.

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