What does "toFixed" do in JavaScript?

In JavaScript, the toFixed() method is used to format a number using fixed-point notation. It converts a number into a string, keeping a specified number of decimal places. This is particularly useful when you need to display numerical values with a consistent level of precision, such as in financial applications or when dealing with measurements.

Here's a breakdown of how toFixed() works:

1. Syntax:

The syntax for using toFixed() is as follows:

number.toFixed(digits)

- number: The number you want to format.

- digits: An integer between 0 and 20 (inclusive) that specifies the number of digits to appear after the decimal point. If this argument is omitted, it's treated as 0.

2. Return Value:

- toFixed() returns a string representation of the number, formatted with the specified number of decimal places. If the number has fewer decimal places than specified, it will be padded with zeros. If the number has more decimal places, it will be rounded to the specified number of decimal places.

3. Rounding Behavior:

- The toFixed() method performs rounding based on the standard rounding rules. If the digit after the specified decimal place is 5 or greater, the last digit is rounded up. Otherwise, it is rounded down.

4. Examples:

Here are some examples to illustrate how toFixed() works:

const num1 = 3.14159;
const formattedNum1 = num1.toFixed(2); // Returns "3.14"
console.log(formattedNum1);

const num2 = 123.4;
const formattedNum2 = num2.toFixed(3); // Returns "123.400"
console.log(formattedNum2);

const num3 = 5.678;
const formattedNum3 = num3.toFixed(0); // Returns "6"
console.log(formattedNum3);

const num4 = 9.999;
const formattedNum4 = num4.toFixed(2); // Returns "10.00"
console.log(formattedNum4);

5. Important Considerations:

- The toFixed() method returns a string, not a number. If you need to perform further calculations, you might need to convert the result back to a number using parseFloat() or Number().

- If the digits argument is not a number or is outside the range of 0 to 20, it will throw a RangeError.

In summary, toFixed() is a useful method for controlling the precision of numbers when displaying them as strings, ensuring consistent formatting and readability.

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