JavaScript Number toPrecision( ) Method

Last Updated : 07 Sep, 2020

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:

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
```
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
```

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>