how to get upto 4 decimal places in javascript code example

Example 1: javascript round decimal 2 digits

var numb = 123.23454;
numb = numb.toFixed(2);

Example 2: js round up decimal

Math.round(3.14159)  // 3
Math.round(3.5)      // 4
Math.floor(3.8)      // 3
Math.ceil(3.2)       // 4