javascript get random element from array

The thing is that the post title is not the actual thing what I need. The answer I need is much more harder.

Ok, so I have very big array of numbers in javascript:

[1, 1.01, 1.02, 1.03, ..., 1.99, 2, ..., 9.98, 9.99, ..., 299.99, 300]

And what I need is to get one of them using random segment. So basically I need random number but the catch is that I need to get random using the lottery style. So the chance to get "1" will be 30 000 (very hight) and the chance to get 1.01 will be 29 999. But the chance to get 300 will be very low according of all numbers in this array.

I hope you will understand the problem and will help me to solve this. As I have mentioned before, this have to be made 100% randomly and I have no idea how to make it..

The solution I had so far:

I was trying to expanse the array by adding multiple same numbers and lower the count of it by each step. So I have added 30000 units of 1 and 29999 units of 1.01 ... and 2 units of 299.99 and one unit of 300. But the array got very large and I came here to find better solution.