JavaScriptで高階関数

例：

function higher_order() {
    var add = function (x, y) {
        return x + y;
    }

    var sub = function (x, y) {
        return x - y;
    }

    calc(1, 5, add);
    calc(7, 6, sub);
}

function calc(x, y, f) {
    return f(x, y);
}

これを，XMLHttpRequestで利用。

function getJson(uri, func) {
    var req = new XMLHttpRequest();

    req.onreadystatechange = function() {
        if (req.readyState == 4 && req.status == 200) {
            var linksJson = req.responseText;
            var data;

            eval("data = " + linksJson);

            func(data);
        }
    }

    req.open("GET", uri, true);
    req.send(null);
}

function process1() {
    var func = function (data) {
        // process
    }

    getJson("hoge.json", func);
}