“this” inside an anonymous function?

Question

Inside John Resig\'s book \"Pro Javascript techniques\" he describes a way of generating dynamic object methods with the below code:

// Create a new user obj         


        

Answer 1

Is this code from the book? I have the book, but I haven't read through it.

It's an error in the book. Check the errata: http://www.apress.com/9781590597279

Inside the anonymous function, this is the global window.

You could make it work by adding .call(this, i) after it.

function User(properties) {
    // Iterate through the properties of the object, and make sure
    // that it's properly scoped (as discussed previously)
    for (var i in properties) {
        (function(i) {
            // Create a new getter for the property
            this["get" + i] = function() {
                return properties[i];
            };
            // Create a new setter for the property
            this["set" + i] = function(val) {
                properties[i] = val;
            };
        }).call(this, i);
    }
}