ex.js

function greet(language, name) {
    var hi;

    switch(language) {
        case "en":
            hi = "Hello";
            break;

        case "pt":
            hi = "Oi";
            break;

        case "de":
            hi = "Hallo";
            break;
     }

     console.log(hi + " " + name);
}

function makeGreet(language) {
    return greet.bind(this, language);
}

var greetEn = makeGreet("en");
greetEn("Gabriel"); // Hi Gabriel

var greetDe = makeGreet("de");
greetDe("Lucas"); // Hallo Lucas