Restrict the number of decimal digits displayed in JavaScript

Question

Restrict the number of decimal digits displayed in JavaScript

Hello, I've got a few floating numbers listed below:

4.3455
2.768
3.67

and I would like to format them as follows:

4.34
2.76
3.67

I am not looking to round the numbers up or down, but rather limit the decimal places shown to 2.

javascript floating-point decimal limit

Answer 1

Answer №1

If you're seeking a way to limit the number of decimal places in JavaScript, check out toFixed:

var num = 4.3455;
alert(num.toFixed(2)); // displays 4.35 -- not quite what you intended!

However, if your goal is to truncate rather than round the number, consider this approach:

var num = 4.3455;
num = Math.floor(num * 100) / 100;
alert(num.toFixed(2)); // shows 4.34

Answer 2

If you're seeking a way to limit the number of decimal places in JavaScript, check out toFixed:

var num = 4.3455;
alert(num.toFixed(2)); // displays 4.35 -- not quite what you intended!

However, if your goal is to truncate rather than round the number, consider this approach:

var num = 4.3455;
num = Math.floor(num * 100) / 100;
alert(num.toFixed(2)); // shows 4.34

Answer 3

Answer №2

When T.J provided an explanation, he mentioned that the toFixed method will round numbers as needed and may add trailing zeroes, which might not always be desired.

(8.87654).toFixed(3);
//-> "8.877"

(8).toFixed(3);
//-> "8.000"

To remove any trailing zeroes, you can simply convert the returned value back to a number. This approach is more straightforward compared to creating your own rounding or truncation logic.

+parseFloat((8.87654).toFixed(3));
//-> 8.877

+parseFloat((8).toFixed(3));
//-> 8

Answer 4

When T.J provided an explanation, he mentioned that the toFixed method will round numbers as needed and may add trailing zeroes, which might not always be desired.

(8.87654).toFixed(3);
//-> "8.877"

(8).toFixed(3);
//-> "8.000"

To remove any trailing zeroes, you can simply convert the returned value back to a number. This approach is more straightforward compared to creating your own rounding or truncation logic.

+parseFloat((8.87654).toFixed(3));
//-> 8.877

+parseFloat((8).toFixed(3));
//-> 8

Answer 5

Answer №3

Exciting news everyone! There has been an alternative available for some time now: toLocaleString()

Although it isn't specifically designed for rounding, there are some useful optional arguments.

minimumIntegerDigits

You can specify the minimum number of integer digits to use, with possible values ranging from 1 to 21; default is set at 1.

minimumFractionDigits

This allows you to set the minimum number of fraction digits to display.

Possible choices span from 0 to 20; for plain number and percent formatting, the default is 0, while for currency formatting, it defaults to the number of minor unit digits specified by the ISO 4217 currency code list (2 if such information is not provided).

maximumFractionDigits

You can choose the maximum number of fraction digits to include in the output.

The range of options goes from 0 to 20; for plain number formatting, the default is determined as the larger value between minimumFractionDigits and 3.

When dealing with currency formatting, the default becomes the larger value between minimumFractionDigits and the number of minor unit digits indicated by the ISO 4217 currency code list (defaulting to 2 if such data is unavailable); meanwhile, for percent formatting, the default is calculated as the larger value between minimumFractionDigits and 0.

minimumSignificantDigits

This option lets you define the minimum number of significant digits to be used.

You have a choice between 1 and 21, with the default being 1.

maximumSignificantDigits

Here, you specify the maximum number of significant digits to display.

The acceptable range is from 1 to 21, with the default set at 21.

Example usage:

var bigNum = 8884858284485 * 4542825114616565
var smallNum = 88885 / 4545114616565

console.log(bigNum) // Output scientific notation

console.log(smallNum) // Output scientific notation

// String
console.log(
  bigNum.toLocaleString('fullwide', {useGrouping:false})
) 

// Return a string, rounded to 12 decimals
console.log(
  smallNum.toLocaleString('fullwide', {maximumFractionDigits:12})
)


// Return a string, rounded to 8 decimals
console.log(
  smallNum.toLocaleString('fullwide', {minimumFractionDigits:8, maximumFractionDigits:8})
)

// Return an Integer, dynamically rounded, JavaScript will convert it back to scientific notation!
console.log(
  +smallNum.toLocaleString('fullwide', {maximumFractionDigits:12})
)

// Return the same Integer without using parseInt for precision!
console.log(
  parseInt(smallNum.toLocaleString('fullwide', {maximumFractionDigits:12}))
)

However, if your aim is rounding, this snippet may help:

function cutDecimals(number,decimals){
  return number.toLocaleString('fullwide', {maximumFractionDigits:decimals})
}

console.log(
  cutDecimals(4.3455,2),
  cutDecimals(2.768,2),
  cutDecimals(3.67,2)
)

Answer 6

Exciting news everyone! There has been an alternative available for some time now: toLocaleString()

Although it isn't specifically designed for rounding, there are some useful optional arguments.

minimumIntegerDigits

You can specify the minimum number of integer digits to use, with possible values ranging from 1 to 21; default is set at 1.

minimumFractionDigits

This allows you to set the minimum number of fraction digits to display.

Possible choices span from 0 to 20; for plain number and percent formatting, the default is 0, while for currency formatting, it defaults to the number of minor unit digits specified by the ISO 4217 currency code list (2 if such information is not provided).

maximumFractionDigits

You can choose the maximum number of fraction digits to include in the output.

The range of options goes from 0 to 20; for plain number formatting, the default is determined as the larger value between minimumFractionDigits and 3.

When dealing with currency formatting, the default becomes the larger value between minimumFractionDigits and the number of minor unit digits indicated by the ISO 4217 currency code list (defaulting to 2 if such data is unavailable); meanwhile, for percent formatting, the default is calculated as the larger value between minimumFractionDigits and 0.

minimumSignificantDigits

This option lets you define the minimum number of significant digits to be used.

You have a choice between 1 and 21, with the default being 1.

maximumSignificantDigits

Here, you specify the maximum number of significant digits to display.

The acceptable range is from 1 to 21, with the default set at 21.

Example usage:

var bigNum = 8884858284485 * 4542825114616565
var smallNum = 88885 / 4545114616565

console.log(bigNum) // Output scientific notation

console.log(smallNum) // Output scientific notation

// String
console.log(
  bigNum.toLocaleString('fullwide', {useGrouping:false})
) 

// Return a string, rounded to 12 decimals
console.log(
  smallNum.toLocaleString('fullwide', {maximumFractionDigits:12})
)


// Return a string, rounded to 8 decimals
console.log(
  smallNum.toLocaleString('fullwide', {minimumFractionDigits:8, maximumFractionDigits:8})
)

// Return an Integer, dynamically rounded, JavaScript will convert it back to scientific notation!
console.log(
  +smallNum.toLocaleString('fullwide', {maximumFractionDigits:12})
)

// Return the same Integer without using parseInt for precision!
console.log(
  parseInt(smallNum.toLocaleString('fullwide', {maximumFractionDigits:12}))
)

However, if your aim is rounding, this snippet may help:

function cutDecimals(number,decimals){
  return number.toLocaleString('fullwide', {maximumFractionDigits:decimals})
}

console.log(
  cutDecimals(4.3455,2),
  cutDecimals(2.768,2),
  cutDecimals(3.67,2)
)

Answer 7

Answer №4

In order to avoid rounding to 2 decimal places, you can utilize the toFixed() method to round to a specific number of decimal places and then remove all digits except for the last two:

let number = 7.893.toFixed(20);
alert(number.slice(0, -18));
//-> 7.89

It is important to note that using this method may result in some inaccuracies if the specified number of decimal places used in toFixed() is less than the actual number of decimals present in the initial number, especially with larger decimal values. For example, (9.99999999999).toFixed(10) will output 10.0000000000. To prevent this issue, make sure to set the decimal places lower than those passed to toFixed(). This adjustment enhances the reliability of @TJ's solution.

Answer 8

In order to avoid rounding to 2 decimal places, you can utilize the toFixed() method to round to a specific number of decimal places and then remove all digits except for the last two:

let number = 7.893.toFixed(20);
alert(number.slice(0, -18));
//-> 7.89

It is important to note that using this method may result in some inaccuracies if the specified number of decimal places used in toFixed() is less than the actual number of decimals present in the initial number, especially with larger decimal values. For example, (9.99999999999).toFixed(10) will output 10.0000000000. To prevent this issue, make sure to set the decimal places lower than those passed to toFixed(). This adjustment enhances the reliability of @TJ's solution.

Answer 9

Answer №5

Heads up! The current solution may not work properly in certain scenarios, like with 4.27 where it incorrectly gives 4.26 as the result.

Check out a reliable solution that always delivers accurate results.

(I thought about leaving this as a comment, but I don't have enough reputation points at the moment)

Answer 10

Heads up! The current solution may not work properly in certain scenarios, like with 4.27 where it incorrectly gives 4.26 as the result.

Check out a reliable solution that always delivers accurate results.

(I thought about leaving this as a comment, but I don't have enough reputation points at the moment)

Answer 11

Answer №6

Utilize the toPrecision method for precise results :)

let num = 67537653.76828732668326;
num = (String(num).indexOf('.') !== -1) ? +num.toPrecision(String(num).indexOf('.') + 2) : +num.toFixed(2);
// => 67537653.76

The number 2 in the second line specifies the decimal places output, and if you want a string as output, simply remove the "+" operator.

Answer 12

Utilize the toPrecision method for precise results :)

let num = 67537653.76828732668326;
num = (String(num).indexOf('.') !== -1) ? +num.toPrecision(String(num).indexOf('.') + 2) : +num.toFixed(2);
// => 67537653.76

The number 2 in the second line specifies the decimal places output, and if you want a string as output, simply remove the "+" operator.

Restrict the number of decimal digits displayed in JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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