Javascript – socket.io Removing specific listener

javascriptsocket.iosockets

I'm using Socket.io v0.9.16 and
Chrome 34

I'm trying to remove a specific listener, or unsubscribe from a specific subscription

Something like this:

socket.on('testComplete',function(data){
    console.log('test complete',data);
}); 

function emitTest(){
    console.log('emitting test');
    socket.emit('test','first emit');
}

function removeListener(){
    socket.removeListener('testComplete');
}

If I call the emitTest function, and then the removeListener function, I still see the 'test complete' message when I call emitTest again. The listener should have been removed, if the socket function even works.

I'm looking for a way to remove a specific listener that actually works.

This answer says that removeListener doesn't work.

Is there any downside to just doing this:

socket.removeListener=function(name){
        if(socket.$events.hasOwnProperty(name)){
            delete socket.$events[name];
        }
    };

I marked an answer as correct, but I'm using the above in my code since it works better with my design.

Best Answer

//To unsubscribe all listeners of an event
socket.off('event-name');

//to unsubscribe a certain listener
socket.off('event-name', listener);

Note that socket.off, socket.removeListener, socket.removeAllListeners, socket.removeEventListener are synonyms.

This is tested on socket.io v1.4.3

Related Solutions

Javascript – How to check if an object has a specific property in JavaScript

I'm really confused by the answers that have been given - most of them are just outright incorrect. Of course you can have object properties that have undefined, null, or false values. So simply reducing the property check to typeof this[property] or, even worse, x.key will give you completely misleading results.

It depends on what you're looking for. If you want to know if an object physically contains a property (and it is not coming from somewhere up on the prototype chain) then object.hasOwnProperty is the way to go. All modern browsers support it. (It was missing in older versions of Safari - 2.0.1 and older - but those versions of the browser are rarely used any more.)

If what you're looking for is if an object has a property on it that is iterable (when you iterate over the properties of the object, it will appear) then doing: prop in object will give you your desired effect.

Since using hasOwnProperty is probably what you want, and considering that you may want a fallback method, I present to you the following solution:

var obj = {
    a: undefined,
    b: null,
    c: false
};

// a, b, c all found
for ( var prop in obj ) {
    document.writeln( "Object1: " + prop );
}

function Class(){
    this.a = undefined;
    this.b = null;
    this.c = false;
}

Class.prototype = {
    a: undefined,
    b: true,
    c: true,
    d: true,
    e: true
};

var obj2 = new Class();

// a, b, c, d, e found
for ( var prop in obj2 ) {
    document.writeln( "Object2: " + prop );
}

function hasOwnProperty(obj, prop) {
    var proto = obj.__proto__ || obj.constructor.prototype;
    return (prop in obj) &&
        (!(prop in proto) || proto[prop] !== obj[prop]);
}

if ( Object.prototype.hasOwnProperty ) {
    var hasOwnProperty = function(obj, prop) {
        return obj.hasOwnProperty(prop);
    }
}

// a, b, c found in modern browsers
// b, c found in Safari 2.0.1 and older
for ( var prop in obj2 ) {
    if ( hasOwnProperty(obj2, prop) ) {
        document.writeln( "Object2 w/ hasOwn: " + prop );
    }
}

The above is a working, cross-browser, solution to hasOwnProperty, with one caveat: It is unable to distinguish between cases where an identical property is on the prototype and on the instance - it just assumes that it's coming from the prototype. You could shift it to be more lenient or strict, based upon your situation, but at the very least this should be more helpful.

Javascript – How to insert an item into an array at a specific index (JavaScript)

You want the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert).

In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join()); // Jani,Hege,Stale,Kai Jim,Borge
arr.splice(2, 0, "Lene");
console.log(arr.join()); // Jani,Hege,Lene,Stale,Kai Jim,Borge

Best Answer

Related Solutions

Javascript – How to check if an object has a specific property in JavaScript

Javascript – How to insert an item into an array at a specific index (JavaScript)

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