How to Round to Two Decimal Places Only if Necessary in Javascript?
There are several ways to round a number to two decimal places only if necessary in JavaScript. The most common way is to use the .toFixed() method. Here's an example:
const num = 3.14159;
const roundedNum = num.toFixed(2); // returns "3.14"
const num2 = 5.0;
const roundedNum2 = num2.toFixed(2); // returns "5.00"
The .toFixed() method returns a string representation of the number rounded to the specified number of decimal places. If the number has fewer decimal places than the argument, it will add trailing zeros to meet the specified number of decimal places.
Another way to round a number to two decimal places only if necessary is to use the Math.round() method in combination with some math. Here's an example:
const num = 3.14159;
const precision = 100; // 10^2
const roundedNum = Math.round(num * precision) / precision; // returns 3.14
const num2 = 5.0;
const roundedNum2 = Math.round(num2 * precision) / precision; // returns 5
In this example, we're multiplying the number by 100 (10^2) to shift the decimal point two places to the right, rounding the result to the nearest integer with Math.round(), and then dividing by 100 to shift the decimal point back two places. This approach can be more precise than using .toFixed(), but it requires more math and can be harder to read.