How to add new quotes to a quote generator website?

I have made a random quote generator website that upon pressing a button will present a quote on command. I also added a text box and button that allows visitors to add their own favorite quotes to show on the website. However I don't know how to exactly enact this feature. The quotes are stored in a Javascript array. So what I'm technically asking is how do I allow website visitors to add in thier quotes to the array via Javascript, and maintain this feature if I were to publish my website online.

var quotes = ["Imagination is more important than knowledge. - Albert Einstein",
"The path towards a free society has not been simple. - Vladimir Putin", 
"Most folks are about as happy as they make up their minds to be. - Abraham Lincoln", 
"Where there is matter, there is geometry. - Johannes Kepler"]