How do you round to 1 decimal place in Javascript?

Question

Can you round a number in javascript to 1 character after the decimal point (properly rounded)?

I tried the *10, round, /10 but it leaves two decimals at the end of the int.

Answer 1

Math.round(num * 10) / 10 works, here is an example...

var number = 12.3456789 var rounded = Math.round(number * 10) / 10 // rounded is 12.3 

if you want it to have one decimal place, even when that would be a 0, then add...

var fixed = rounded.toFixed(1) // fixed is always to 1 d.p. // NOTE: .toFixed() returns a string!  // To convert back to number format parseFloat(number.toFixed(2)) // 12.34 // but that will not retain any trailing zeros  // So, just make sure it is the last step before output, // and use a number format during calculations! 

EDIT: Add round with precision function...

Using this principle, for reference, here is a handy little round function that takes precision...

function round(value, precision) {     var multiplier = Math.pow(10, precision || 0);     return Math.round(value * multiplier) / multiplier; } 

... usage ...

round(12345.6789, 2) // 12345.68 round(12345.6789, 1) // 12345.7 

... defaults to round to nearest whole number (precision 0) ...

round(12345.6789) // 12346 

... and can be used to round to nearest 10 or 100 etc...

round(12345.6789, -1) // 12350 round(12345.6789, -2) // 12300 

... and correct handling of negative numbers ...

round(-123.45, 1) // -123.4 round(123.45, 1) // 123.5 

... and can be combined with toFixed to format consistently as string ...

round(456.7, 2).toFixed(2) // "456.70"