var my_val=56.879654
document.write(my_val.toFixed(4)); // Output 56.8797
my_val is the variable which stores the number. Here we are formatting the number upto 4 decimal places.
var my_val=11.257;
document.write (my_val.toFixed(2)); // output 11.26
document.write ("<br>----<br>");
var my_val=11.25;
document.write (my_val.toFixed(1)); // output 11.3
document.write ("<br>----<br>");
var my_val=11.978;
document.write (my_val.toFixed(4)); // output 11.9780
document.write ("<br>----<br>");
While using any data coming from a text box or any other sources, we have to use parseInt or parseFloat functions to convert the data from string to integer or float before using toFixed function.