The problem of method extraction and invocation in javascript

scenario :

there is an object, and the method foo () is added through the prototype keyword.

var Graph = new Graph();
//foo
Graph.prototype.foo = function(){
    ...
}
//fun
Graph.prototype.fun = function(){
    ...
}

now the logic in the foo () method is too complex, so I want to extract some functional code into a new method subfoo () .
what should I do at this time?

this is what I did at first:

var Graph = new Graph();
Graph.prototype.foo = function(){
    ....
    function subfoo(){
        //fun()
        this.fun();    //graphfun(), fun(), thiswindow, graph
    }
    //subfoo()
    subfoo.call(this);    //thisgraph, subfoo()
}

however, when I call another Graph.prototype.fun method in subfoo () , when I go to fun () , the this pointer becomes window , even if I use call . What you want, of course, is to point to graph.

all the time.

maybe my idea is wrong. what should I do in scenarios like this that require extraction methods?
there is no such thing as java which is really object-oriented and easy to understand.

function Graph() {} var Graph = new Graph(); Graph.__proto__.foo = function() { console.log('old foo', this); return this; } Graph.__proto__.fun = function() { console.log('old fun', this); return this; } Graph.__proto__.foo = function() { console.log('new foo', this); function subfoo() { console.log('subfoo', this); this.fun(); return this; } subfoo.call(this); return this; } Graph.foo();

for (var i = 0; i < edges.length; iPP) { var edge = edges[i]; if (edge.data != null && edge.data.type != null) { console.log("this.edgeTypeSet"); console.log(this.edgeTypeSet); if (edge.data.type in this.edgeTypeSet) { console.log("this.edgeTypeSet:"); console.log(this.edgeTypeSet); this.addEdge(edge); } } else { //type, , this.addEdge(edge); } }