merging object literals

Default params

function myFunc(paramObject) {
    var defaultParams = {
        param1: "first string",
        param2: "second string",
        param3: "third string"
    };

    var finalParams = _.extend(defaultParams, paramObject);

    console.log(finalParams.param1,
                finalParams.param2,
                finalParams.param3);
}

// Outputs:
// "My own string" and "second string" and "third string"
myFunc({param1: "My own string"});

Merging

var object = $.extend({}, object1, object2);