What does parseInt do in JavaScirpt code example

Example 1: Javascript string to int

var myInt = parseInt("10.256"); //10
var myFloat = parseFloat("10.256"); //10.256

Example 2: javascript parseint

var myInt = parseInt("12.345");
//myInt = 12

var myFloat = parseFloat("12.345");
//myFloat = 12.345

var myFloat = parseFloat("12.345,50"); //<-- pay attention!
//myFloat = 12.345

var myFloatCrazy = parseFloat(0.1+0.2); //<-- pay MORE attention!
//myFloat = 0.30000000000000004