“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

Here is how to do it. You need to save the context into another variable. The other option is not to do this inner function that you are doing in the for loop.

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

Option 2:

// Create a new user object that accepts an object of properties
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 ) {
       // 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;
       };
    }
}