How to compare two big number in javascript

Why below code output result is equal? How to compare?

var num1 = 340282000000000000000000000000000000001
var num2 = 340282000000000000000000000000000000000  // 3.402823E+38
if(num1 == num2) {
    console.log('num1 equal to num2');
} else if(num1 > num2) {
    console.log('num1 bigger than num2');
} else {
    console.log('num1 lower than num2')
}