Proxy

An object representing another object.

• Proxy provides a surrogate or placeholder for another object to control access to it.

• Proxy means 'in place of' or 'representing' or 'on behalf of'.

• The proxy is the object that is being called by the client to access the real object behind the scene.

• In this pattern, a class represents functionality of another class.

• Most frequently used in JavaScript.

EX:
function GeoCoder() {
 
    this.getLatLng = function(address) {
        
        if (address === "Amsterdam") {
            return "52.3700° N, 4.8900° E";
        } else if (address === "London") {
            return "51.5171° N, 0.1062° W";
        } else if (address === "Paris") {
            return "48.8742° N, 2.3470° E";
        } else if (address === "Berlin") {
            return "52.5233° N, 13.4127° E";
        } else {
            return "";
        }
    };
}
 
function GeoProxy() {
    var geocoder = new GeoCoder();
    var geocache = {}; 
    return {
        getLatLng: function(address) {
            if (!geocache[address]) {
                geocache[address] = geocoder.getLatLng(address);
            }
            return geocache[address];
        },
        getCount: function() {
            var count = 0;
            for (var code in geocache) { count++; }
            return count;
        }
    };
};

var geo = new GeoProxy();
 
    // geolocation requests 
    geo.getLatLng("Paris");
    geo.getLatLng("London");
    geo.getLatLng("London");
    geo.getLatLng("London");
    geo.getLatLng("London");
    geo.getLatLng("Amsterdam");
    geo.getLatLng("Amsterdam");
    geo.getLatLng("Amsterdam");
    geo.getLatLng("Amsterdam");
    geo.getLatLng("London");
    geo.getLatLng("London"); 
    console.log("\nCache size: " + geo.getCount());

Real time Ex:

Real time Example for Proxy Pattern