JavaScript Number toPrecision( ) Method

Below is the example of the Number toPrecision( ) Method.

• Example:

  
  <script type="text/javascript">
      var num=213.45689;
      document.write(num.toPrecision(3));
  </script>
• Output:

  213

The toPrecision() method in Javascript is used to format a number to a specific precision or length. If the formatted number requires more digits than the original number then decimals and nulls are also added to create the specified length.

Syntax:

number.toPrecision(value)

The toPrecision() method is used with a number as shown in above syntax using the ‘.’ operator. This method will format a number to a specified length.

Parameters: This method accepts a single parameter value. This parameter is also optional and it represents the value of the number of significant digits the user wants in the formatted number.

Return Value: The toPrecision() method in JavaScript returns a string in which the number is formatted to the specified precision.

Below are some examples to illustrates toPrecision() method:

1. Passing no arguments in the toPrecision() method: If no arguments is passed to the toPrecision() method then the formatted number will be exactly the same as input number. Though, it will be represented as a string rather than a number.
   Code# 1:

   
   <script type="text/javascript">
       var num=213.45689;
       document.write(num.toPrecision());
   </script>

   Output:

   213.45689

2. Passing an argument in the toPrecision() method: If the length of precision passed to the toPrecision() method is smaller than the original number then the number is rounded off to that precision.
   Code# 2:

   <script type="text/javascript">
       var num=213.45689;
       document.write(num.toPrecision(4));
   </script>

   Output:

   213.5

3. Passing an argument which results in addition of null in the output: If the length of precision passed to the toPrecision() method is greater than the original number then zero’s are appended to the input number to meet the specified precision.
   Code# 3:

   <script type="text/javascript">
       var num=213.45689;
       document.write(num.toPrecision(12));
   
       var num2 = 123;
       document.write(num2.toPrecision(5));
   </script>

   Output:

   213.456890000
   123.00
   

Note: If the precision specified is not in between 1 and 100 (inclusive), it results in a RangeError.

Supported Browsers:

• Google Chrome 1 and above
• Internet Explorer 5.5 and above
• Firefox 1 and above
• Apple Safari 2 and above
• Opera 7 and above