gistfile1.js

// put inside a .js file, referenced on the page by the resource's URI
// Create a local variable to hold `jQuery', so you type less.
// Using $ is stupíd, since that symbol is (by ES5 specs) reserved for
// machine-generated code.
void function(j) {
    function get_data() {
        // use functions to abstract code sections
        function get_item(i)  { return data[i].high + '<br>' + ~~(Math.random() * 111) }
        function update(idx)  { return j('#high').html(get_item(idx))                  }
        function process(data){ return j.each(data, update)                            }

        return j.getJSON('script.php', process)
    }
    get_data()
    var auto_refresh = setInterval(get_data, 5000)
}(jQuery)