Javascript: this, that, self

Often one comes across javascript codes like the following:

var that = this;

or

var self = this;
 
The above code usage is due to 2 features of Javascript:
  1. binding is always explicit.  For example, if you don’t explicit bind a variable to an object, Javascript may look for the variable in window object.
  2. Keyword this loses the binding/context when you are accessing a method through a reference.

The solution is to leverage “closures”, letting code instead of a block access variables/methods declared in scopes surrounding that code block.

processItems: function() {
var that = this;
this.items.each(function(item) {
// Process item
that.markItemAsProcessed(item);
});

}

 

Reference:

http://alistapart.com/article/getoutbindingsituations

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