How to call a JavaScript object method from within a method

Question

I'm just trying to figure out how I can call a javascript object method from within a method of the same object as below..

var testObject = {
    method1 : function() {
        var connectionAddr = "ws://localhost:8003";
        socket = new WebSocket(connectionAddr);
        socket.onmessage = function(event) {
            method2();
        }

    },

    method2: function() {
        this.method1();
    }
}

Changed my question as I realise when using this.method2() it is refering to the WebSocker object.

Niccolò Campolungo · Answer 1 · 2013-08-02T09:44:42.353

4

There are a lot of answers in SO for problems like this, you should do a little research(on SO or on Google) before asking here.

var testObject = {
    method1 : function() {
        var connectionAddr = "ws://localhost:8003",
            self = this;
        socket = new WebSocket(connectionAddr);
        socket.onmessage = function(event) {
            self.method2();
        }
    },

    method2: function() {
        this.method1(); //something like this would cause an infinite call stack, you should change this code
        //this refers to the current object, so has properties method2 and method2
    }
}

You need to reference to the current object using this, otherwise the JS Engine will look for a function named method1 in any of the higher scopes, all the way up to the global namespace. If such a function object (or such a name doesn't exist), method1 will be evaluated to undefined.

edited Aug 02 '13 at 09:44

answered Aug 02 '13 at 09:32

Niccolò Campolungo

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I did look but the examples I saw were using objects within objects not as properties, but thanks for the answer. – Jack Aug 02 '13 at 09:37
@Jack: since functions are objects, you are using objects in objects, too... – Elias Van Ootegem Aug 02 '13 at 09:41
Changed the question, sorry for the original dumb one. – Jack Aug 02 '13 at 09:42
Changed the answer, pay attention to the comments in the code. In that case you need to save a reference to the current this to use it in a different scope. – Niccolò Campolungo Aug 02 '13 at 09:45
Thanks for the help, I do understand it would end in an infinate loop, I just quickly changed it. – Jack Aug 02 '13 at 09:52

Dawood Awan · Accepted Answer · 2016-02-11T14:17:51.487

1

try this

var testObject = {
        method1 : function() {
            var connectionAddr = "ws://localhost:8003";
            socket = new WebSocket(connectionAddr);
            socket.onmessage = function(event) {
                testObject.method2();
            }

        },

        method2: function() {
            testObject.method1();
        }
    }

edited Feb 11 '16 at 14:17

answered Aug 02 '13 at 09:50

Dawood Awan

7,051
10
56
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This is the cleanest way I believe thanks!! – Jack Aug 02 '13 at 09:54

jidexl21 · Answer 3 · 2013-08-02T10:05:45.207

updated to match your current question: good part is you can add additional functions and call any one of them with this method;

var testObject = {
   method1 : function() {
    var connectionAddr = "ws://localhost:8003",
        self = this;
    socket = new WebSocket(connectionAddr);
    socket.onmessage = function(event) {
        self['method2']();
    }
},

method2: function() {
    this['method1']();
}
}

How to call a JavaScript object method from within a method

3 Answers3