How to Round Numbers to Two Decimal Places in JavaScript?

Rounding to Two Decimal Places, if Necessary in JavaScript

You want to round a number up to two decimal places, but only if it has more than two decimal places. For instance, 10 should remain unchanged, 1.7777777 should become 1.78, and 9.1 should stay as is.

Solutions:

There are two approaches you can take in JavaScript:

1. Using Math.round()

• Multiply the number by 100 to shift the decimal point two places to the right.
• Use Math.round() to round the result.
• Divide the rounded result by 100 to shift the decimal point back two places to the left.

Math.round(num * 100) / 100

2. Using Number.EPSILON

• This method is more accurate than the previous one for values close to integers.
• Add Number.EPSILON (a tiny positive number) to the number to avoid rounding issues with values like 1.005.
• Multiply by 100, round using Math.round(), and then divide by 100.

Math.round((num + Number.EPSILON) * 100) / 100

Sample Input and Output:

Input	Using Math.round()	Using Number.EPSILON
10	10	10
1.7777777	1.78	1.78
9.1	9.1	9.1
1.005	1	1.01

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