Block (programming): Difference between revisions

Revision as of 18:57, 16 June 2021

Revision as of 19:11, 16 June 2021

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==Hoisting==

In some languages, a variable can be declared at function scope even within enclosed blocks. For example, in Javascript, variables declared with <code>var</code> have function scope.

In a few circumstances, code in a block is evaluated as if the code were actually at the top of the block or outside the block. This is often colloquially known as ''hoisting'', and includes:

* [[Loop-invariant code motion]], a compiler optimization where code in the loop that is invariant is evaluated before the loop;

* [[Variable hoisting]], a scope rule in JavaScript, where variables have function scope, and behave as if they were declared (but not defined) at the top of a function.

==See also==