10. The Global environment and the global object #

Created Sunday 20 February 2022

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Global execution context #

• All code in JavaScript is run inside an execution context (or activation record).
• The JavaScript engine always provides a base execution context in the form of a lexically global object.
• All code outside a function is attached to this global object as a name-value pair.
• In the browser, this engine provided global object is named window.

this keyword #

The this keyword refers to the current execution context. In case of global code, this points (is equal) to window.

The 4 things for any location #

Every location in the code has 4 things associated/accessible with it:

1. Global execution context (GEC). In the browser, this is window.
2. Current execution context, referred by this.
3. Outer environment (=null for the global execution context).
4. The code in the current execution context.