如何使用JSON检索OpenWeatherMap数据？

I've been trying to write a program in JavaScript that can retrieve weather data from OpenWeatherMap using JSON. I'm pretty new to JSON, but I think that I understand the logic behind it. However, when I click the "Get JSON" button, nothing happens. It's possible that "data.temp" in the getJSON function is incorrect, but if I'm understanding correctly, it seems like it should at least print the word "Temperature:" HTML and JavaScript are enclosed below, any help is appreciated.I've been trying to write a program in JavaScri