How to round float numbers in JavaScript
In this tutorial, we will learn how to round float numbers in JavaScript.
Rounding float numbers in JavaScript
Variables used in code
- x – float number. type Number(js)
let x = 3.14159
Rounding float numbers to the nearest integer
The built-in function Math.round() is used here.
console.log(Math.round(x))
Output:
3
Rounding float number to n decimal places
Method 1
The inbuilt function toFixed() is used here.
let n = 2 console.log(Number(parseFloat(x).toFixed(n)))
Method 2
The toFixed() method returns the float number’s string format. To avoid redundant Number – String – Number conversions we use this function.
let n = 3 function roundOf(num,pos){ let power = 10**pos return Math.round(num*power)/power } console.log(roundOf(x,n))
Output:
3.14
Truncating float number
Truncation is a numerical approximation method. It is less time-consuming than rounding, but it does not always provide the most accurate approximation to the original number.
Truncating float number to an integer
The built-in function Math.trunc() is used here.
console.log(Math.trunc(x))
Output:
3
Truncating float number after n decimal places
To complete the task, we use a custom function.
let n = 3 function trunc(num,pos){ let n = num.toString() return Number(n.slice(0,n.indexOf('.')+pos)) } console.log(trunc(x,n))
Output:
3.142
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