[memo/Js] utility and object composition

original source from http://9eye.net/entry/Scope-in-javascript-3

/**
 * @author mulriver
 */
//    utility method for any objects
function _check(msg){
    this.value.println(msg);
}

// creating object 'obj'
var obj = {
    value: 10,
    check: _check // set utility method to member method
}

// define the constructor of 'func' function object
var func = function(){
    this.value = 20;    // define member variable 'value'
}
func.prototype.check1 = function(msg){
    obj.check(msg);    // using object 'obj' for member method (it's object composition technique)
}
func.prototype.check2 = obj.check;    // set object 'obj'`s method to member method

var newFunc = new func();    // get a instance of object 'func'

newFunc.check1("indirect");    // using object 'obj' directly. => 10
newFunc.check2("direct");    // using method of object 'obj' => 20
newFunc.check2.call(obj, "call");    // using a one`s member method with other`s scope => 10
_check.apply(newFunc, ["apply"]);    // using a utility method with scope => 20