Number.prototype.toLocaleString() in JavaScript

Number.prototype.toLocaleString()

The JavaScript function ‘number.toLocaleString(locales, options)’ is a flexible way to format numbers by locale-specific conventions. Developers can add thousands of separators, specify the number of decimal places, and format numerical values as currency or percentages, among other customizations. The breakdown of its two parameters is as follows:

Locales

A string with a BCP 47 language tag or an array of strings with this tag indicates the locales to use for formatting. The formatting rules, including the thousands separator and decimal separator, are controlled by this parameter. The default locale is applied if this parameter is left blank or set to undefined.

Example 1

• Javascript

Javascript

const number = 1234567.89;
const formatted = number.toLocaleString('en-US');
console.log(formatted);

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Output

Example 2

• Javascript

Javascript

const number = 1234567.89;
const formatted = number.toLocaleString(['fr-FR', 'en-US']);
console.log(formatted); 

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Output

Options 

An object with properties defining extra formatting choices. You can modify how the number is displayed by setting one of these options, the number of decimal places, configuring currency symbols, and more.

Example 1

• Javascript

Javascript

const number = 1234.56;
const formatted = number.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
console.log(formatted);

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Output

Example 2

• Javascript

Javascript

const number = 1234.56789;
const formatted = number.toLocaleString('en-US', { maximumFractionDigits: 2 });
console.log(formatted); 

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Output

Frequently Asked Questions

Are there any browser compatibility issues with toLocaleString()?

Modern browsers generally support toLocaleString(), but some older browsers may not support it at all or may behave differently. Testing in your target browsers is crucial, and you should consider using polyfills or libraries for consistent formatting.

How can I handle non-numeric input with toLocaleString()?

Number formatting is supported by the toLocaleString() function. Non-numeric input may cause unexpected behavior or errors if you pass it. Make sure the values you pass to this function are real numbers.

Can I use toLocaleString() for date and time formatting as well?

toLocaleString() is primarily used for number formatting. You should use Date.prototype.toLocaleString() or other date and time formatting functions for date and time formatting.

Conclusion

In this article, we learn about Number.prototype.toLocaleString() in JavaScript. We also learn about JavaScript. We concluded the article Number.prototype.toLocaleString() and their examples.

To better understand the topic, refer to 

• JavaScript Numbers 
• Date Object in Typescript 
• Object Prototype 
   

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