javascript get random line from text file

var ret = "data-123".replace('data-','');
console.log(ret);   //prints: 123

price = 33.3
with open("Output.txt", "w") as text_file:
    text_file.write("Purchase Amount: %s price %f" % (TotalAmount, price))

d = {}
with open("file.txt") as f:
    for line in f:
       (key, val) = line.split()
       d[int(key)] = val

$.get('txt/messages.txt', function(txt) {
var lines = txt.responseText.split("\n");
var randLineNum = Math.floor(Math.random() * lines.length);
return lines[randLineNum]; // random line from the text file
});

input()