how to get first 3 letter in a string in javascript code example

Example 1: javascript get first character of string

var str="Hello Folks!"
var firstStringChar = str.charAt(0); //H

Example 2: js substring first 4 numbwe

mystring = "9862 ....... -pack size 1 - SST Unspun Label (Roll) CAT#: 9862";

mystring = mystring.substring(0, 4);

alert(mystring.trim());