Understanding keyword `this` Warm Up

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Warm Up

Write down everything that you know about this in JavaScript Where have you seen/utilized the word this in your JavaScript projects thus far?

• Used this in classes.... working with mythical creatures
• There is implicit binding/ explicit/ default binding
• This refers to the current context of the code

RULE 1

Is the function called with new (new binding)? => this is the newly constructed object

RULE 2

Is the function called with call, apply, or bind? => this is the explicitly specified object.

RULE 3

Is the function called as a method within an object (implicit binding) => this is that context object.

RULE 4

Do no other rules apply? => default this (default binding) is the global object (undefined in strict mode)

THERE ARE EXCEPTIONS:

• indirect references to functions
• lexical this (working with es6 arrow functions)
• event handlers (JS libraries like jquery will often force callbacks to have a this that may reference something you don't expect)