If the this mechanism is so confusing, even to seasoned JavaScript developers, one may wonder why it's even useful? Is it more trouble than it's worth? Before we jump into the how, we should examine the why. For clarity, I will always use this to refer to the special keyword, and 'this' or this or this otherwise. So, it can be very difficult, especially verbally, to determine whether we are using 'this' as a pronoun or using it to refer to the actual keyword identifier. But what exactly are objects, and why do we need to point to them We will explore objects in detail in this chapter. In Chapters 1 and 2, we explained how the this binding points to various objects depending on the call-site of the function invocation. Note: The word 'this' is a terribly common pronoun in general discourse. You don’t know JS with Kyle Simpson a week of JavaScript workshops with a world renowned expert at GFT Warsaw office. You Don’t Know JS: this & Object Prototypes Chapter 3: Objects. JavaScript's this mechanism isn't actually that advanced, but developers often paraphrase that quote in their own mind by inserting 'complex' or 'confusing', and there's no question that without lack of clear understanding, this can seem downright magical in your confusion. It's a special identifier keyword that's automatically defined in the scope of every function, but what exactly it refers to bedevils even seasoned JavaScript developers.Īny sufficiently advanced technology is indistinguishable from magic. One of the most confused mechanisms in JavaScript is the this keyword. You Don't Know JS Yet: Objects & Classes - 2nd Edition Chapter 1: this Or That? NOTE:Įverything below here is previous text from 1st edition, and is only here for reference while 2nd edition work is underway.

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