Peter Michaux has written about the Lazy Function Definition Pattern.
His article takes you down the path of implementing a simple problem:
Write a function foo that returns a Date object that holds the time that foo was first called.
After critiquing 3 iterations he ends up with:
JAVASCRIPT:
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var foo = function() {
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var t = new Date();
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foo = function() {
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return t;
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};
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return foo();
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};
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He then uses the technique to implement getScrollX, and to talk about how you can use defineGetter in certain browsers to simulate lazy definition for properties that aren’t functions.