javascript pass object method to different object method

Question

I have an object of type bar which has an Array of many foos.

I want to be able to call a method of foo dynamically - I could do this with eval by passing a string, but I would rather get a handle on how to pass the function.

Am I - conceptually - doing this the right way?

var foo = function() {
    this.methodA = function() {
        return "a";
    };
    this.methodB = function() {
        return "b";
    };
};

var bar = function() {
    var foos = [];

    this.construct = function() {
        foos[0] = new foo();
    }; this.construct();

    this.callFoo = function(f) {
        return foos[0].f();
    };
};

b = new bar();
b.callFoo(foo.methodA); //<-- This doesn't work
b.callFoo(methodA); //<-- Or this

Raynos · Accepted Answer · 2011-04-21 18:15:22Z

2

your leaking globals everywhere.

// global leak
foo = function() {

    // global leak
    methodA = function() {
        return "a";
    };
    // global leak
    methodB = function() {
        return "b";
    };
};
// global leak
bar = function() {
    var foos = [];
    // global leak
    construct = function() {
        foos[0] = new foo();
    };construct();

    this.callFoo = function(f) {
        return foos[0].f();
    };
};

b = new bar();
b.callFoo(foo.methodA); //<-- This doesn't work
b.callFoo(methodA); //<-- Or this

To answer the actual question try this.

var foo = function() {
    return {
        methodA: function() { return "a"; },
        methodB: function() { return "b"; }
    };
}

var bar = function() {
    var foos = [];

    return {
        construct: function() {
            foos.push(foo());
        },
        callFoo = function(name) {
            return foos[0][name]();
        }
    }
}

b =  bar();
b.callFoo("methodA");

answered Apr 21, 2011 at 18:15

Raynos

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4 Comments

willoller Over a year ago

Aah accessing the function as an array element. Awesome.

willoller Over a year ago

As for the globals in my real code I'm using this.callFoo(), this.construct(), etc - doesn't that have the same result as declaring with var?

Raynos Over a year ago

@willoller you have to do this.construct = .... construct = ... writes to global scope instead.

willoller Over a year ago

Yeah that's what I meant. Thanks!

Naftali · Accepted Answer · 2011-04-21 18:12:05Z

0

try this:

bar = function() {
    var foos = [];

    construct = function() {
        foos[0] = new foo();
    };construct();

    this.callFoo = function(f) {
        return foos[0][f].apply(foos[0]);
    };
};

answered Apr 21, 2011 at 18:12

Naftali

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