In this article, we will explore the JavaScript program to format numbers as currency strings and learn how to use it in your web development projects.

What is a Currency String?

A currency string is a string representation of a number that is formatted in a specific way to represent a currency value. A currency string typically contains a currency symbol, such as “$” or “€,” followed by the number, separated by a comma or a period. In addition, the number may be rounded to a specific number of decimal places and may include a thousand separator, such as a comma.

1. Method 1: Using the toFixed()

The simplest method for formatting numbers as currency strings in JavaScript is the toFixed() method. This method allows you to specify the number of decimal places to be displayed, and returns a string representation of the number. For example, the following code will format the number 123.456 as a currency string with two decimal places:

				
					var number = 123.456;
var currencyString = number.toFixed(2);
console.log(currencyString); // Output: "123.46"

2. Method2: Using the toLocaleString()

Using the toLocaleString() method is very simple. You simply pass the number you want to format as a currency string to the method, and it returns the formatted string. For example:

				
					let amount = 123456.789;
let currency = amount.toLocaleString("en-US", {style: "currency", currency: "USD"});
console.log(currency); // "$123,456.79"

In this example, we have a variable “amount” that contains the number we want to format as a currency string. We then call the toLocaleString() method on the amount variable and pass in two arguments. The first argument is the locale, which in this case is “en-US”, for the English language in the United States. The second argument is an options object that specifies the style of the currency string and the currency symbol to use.

The options object has two properties: “style” and “currency”. The “style” property is set to “currency” to specify that the string should be formatted as a currency string, and the “currency” property is set to “USD” to select the currency symbol to use.

3. Using the Intl.NumberFormat

The Intl.NumberFormat object is another method for formatting numbers as currency strings in JavaScript. This object allows you to specify the locale and the formatting options for the number, and returns a string representation of the number. For example, the following code will format the number 123.456 as a currency string for the en-US locale:

				
					var number = 123.456;
var numberFormat = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
var currencyString = numberFormat.format(number);
console.log(currencyString); // Output: "$123.46"

Best Practices for Formatting Currency Strings in JavaScript

Now that you know the different methods for formatting numbers as currency strings in JavaScript, it is essential to understand the best practices for ensuring that your currency strings are accurate and consistent.

  1. Use a consistent number of decimal places: When formatting numbers as currency strings, it is important to use a consistent number of decimal places throughout your code. This helps to avoid confusion and inconsistencies when dealing with monetary values.
  2. Use appropriate symbols for your currency: When formatting numbers as currency strings, it is important to use the proper symbols for your currency. For example, use the “$” symbol for US dollars, and the “€” symbol for euros.
  3. Be mindful of locale-specific formatting: When using the toLocaleString() method or the Intl.NumberFormat object to format numbers as currency strings, it is important to be mindful of the locale-specific formatting options. For example, some locales use a period as the decimal separator, while others use a comma.
  4. Consider using a library: If you need to format numbers as currency strings in a complex way, it may be helpful to use a library such as Numeral.js. This library provides a wide range of formatting options and can help to simplify your code.

By following these best practices, you can ensure that your currency strings are accurate and consistent, and that your code is easy to maintain and understand.

Implementing Currency Formatting in Your Application

Now that we have created a custom function for formatting numbers as currency strings, we can use it in our application wherever we need to display currency values. The following code shows an example of how to use the formatCurrency() function on an HTML page:

				
					<p>The cost of the item is <span id="cost">123456.78</span></p><!-- Ezoic - wp_longer_content - longer_content --><div id="ezoic-pub-ad-placeholder-114" data-inserter-version="2"></div><!-- End Ezoic - wp_longer_content - longer_content --><!-- Ezoic - wp_longer_content - longer_content --><div id="ezoic-pub-ad-placeholder-115" data-inserter-version="2"></div><!-- End Ezoic - wp_longer_content - longer_content -->

<script>
  let cost = document.getElementById("cost").innerHTML;
  document.getElementById("cost").innerHTML = formatCurrency(cost);
</script>

In this example, we use the getElementById() method to select the <span> element with the ID of "cost". Then we use the innerHTML property to update the text of the component with the formatted currency value.

Choosing the Best Method for Your Needs

Formatting numbers as currency strings in JavaScript can be done in several ways, each with its benefits and limitations. However, by understanding the basics of number formatting in JavaScript and the different methods for formatting numbers as currency strings, you can choose the best solution for your needs and ensure that your project runs smoothly and effectively.


Thanks for reading. Happy coding!