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Scope and Closures: JavaScript: Uncharted

Courses JavaScriptScope and Closures

Scope and Closures

Resolve names through nested scopes, capture lexical environments, and build private stateful functions with closures.

JavaScript
Unit 11 of 20
20 lessons
176 min
420 XP

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Lessons

20 total

1Rooms and WindowsPredict which nested scopes can read names declared in surrounding scopes.InteractiveConcept7 min20 XPOpen
2Braces Make RoomsUse let and const to create names limited to a block.CodeConcept8 min20 XPOpen
3Functions Are Private RoomsKeep parameters and local variables private to the function that declares them.CodeConcept8 min20 XPOpen
4Which x Wins?Predict how a block-local declaration shadows an outer name.InteractiveConcept7 min20 XPOpen
5Reading Out, Writing InDistinguish assigning to an outer variable from shadowing it with a new declaration.CodeConcept9 min20 XPOpen
6The Lookup ChainTrace name resolution through block, function, and outer scopes.CodeConcept8 min20 XPOpen
7Resolve the NameArrange the search order JavaScript uses to resolve a name.InteractiveConcept7 min20 XPOpen
8The BackpackBuild a counter factory whose returned function closes over a private count.CodeConcept10 min20 XPOpen
9Two Independent CountersProve that separate factory calls create independent closure state.CodeConcept9 min20 XPOpen
10What Got Captured?Predict the values retained by closures created from separate factory calls.InteractiveConcept7 min20 XPOpen
11Greeter FactoryCreate functions that close over different greeting parameters.CodeConcept8 min20 XPOpen
12The Piggy BankUse a closure to expose controlled operations while keeping balance private.CodeConcept10 min20 XPOpen
13Closures in CallbacksCreate callback functions that remember the context present when they were made.CodeConcept9 min20 XPOpen
14Explain the BackpackExplain closures using lexical scope, retained variables, and later function calls.InteractiveConcept9 min20 XPOpen
15once() and Only OnceBuild a closure wrapper that invokes a function once and reuses its first result.CodePractice11 min20 XPOpen
16Remember the AnswerCache function results in a private closure object keyed by input.CodePractice11 min20 XPOpen
17The var Loop ClassicPredict how var and let produce different captured loop bindings.InteractiveConcept9 min20 XPOpen
18Settings MakerCreate a formatter configured by values captured at factory time.CodePractice10 min20 XPOpen
19Spot the Accidental GlobalIdentify an assignment that is missing a local declaration.InteractiveConcept7 min20 XPOpen
20Closures Mastery CheckBuild independent private trackers that combine lexical scope and closure state.CodeMastery check12 min40 XPOpen

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