Question

I use this snippet in Javascript like 100 times a day to have a closure on the enclosing object:

Class.prototype.Method = function(arg){
    var Ta = this;
    var e = function(){
        Ta.doSomething(arg);
    };
};

it there a way to avoid the Ta variable and still refere to the “outer” (is this word correct?) object?

Answer 1

a) You could continue using this approach with more meaningful variable names. Using that is a common convention — it’s indicative that your variable is just another “this” value, but for another function scope.

b) You can use a function bind utility. Some JavaScript libraries come with one. Or you can simply roll your own:

function bind(fn, scope) {
    return function () {
        fn.apply(scope, arguments);
    };
}

// for your example:
Class.prototype.Method = function(arg) {
    var e = bind(function() {
        this.doSomething(arg);
    }, this);
};

// Alternatively, extend the Function prototype (may raise some eyebrows):

Function.prototype.bind = function (scope) {
    var fn = this;
    return function () {
        fn.apply(scope, arguments);
    };
};

// for your example:
Class.prototype.Method = function(arg) {
    var e = function() {
        this.doSomething(arg);
    }.bind(this);
};

Update:
As @Pointy noted, bind is actually part of a new version of the JavaScript spec, getting picked up by modern browsers already: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind