How to round float numbers in javascript?

Use toFixed() function.

(6.688689).toFixed(); // equal to "7"
(6.688689).toFixed(1); // equal to "6.7"
(6.688689).toFixed(2); // equal to "6.69"

Number((6.688689).toFixed(1)); // 6.7

var number = 6.688689;
var roundedNumber = Math.round(number * 10) / 10;