Back in March I wrote a post "Understanding Constructor Functions in Javascript and This keyword" in which, while explaining the concept of this in Javascript, I stated that it is impossible to tell what the this keyword references by just looking at the function definition. You only get to decide or know what the this keyword refers to, by the way the function is called. Call the function one way, and have this refer to one object, call it another way and you can have it refer to a totally different object. Showing that in Javascript, this is a context-indicator.
I mentioned that normal calling of a function (i.e. have a function fx, call it via fx()) and calling with the new keyword i.e. (new fx()) are some of the various ways to call a Javascript function and have the this keyword switch context.
There are 3 other ways a Javascript function can be called with the ability to determine what this keyword references. call, apply and bind. To be technically specific:Function.prototype.call, Function.prototype.apply, and Function.prototype.bind.
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