Some type conversion methods in JavaScript

TypeConversionMethods.js

var numberContent = ~~"1";
var stringContent = ~~"string sample";
var stringContent2 = +"string sample 2";
var booleanContent = !!"false";

console.log(typeof numberContent); //"number"
console.log(numberContent); //1
console.log(typeof stringContent); //"number"
console.log(stringContent); //0, but should be NaN!
console.log(typeof stringContent2); //"number"
console.log(stringContent2); //NaN, this is what it should be.
console.log(typeof booleanContent); //"boolean"
console.log(booleanContent); //true