https://foxipa.com/en/javascript/exercise/code-completion/ Complete focused JavaScript snippets as you learn variables, expressions, control flow, functions, and beyond. Hugo en-US https://foxipa.com/en/javascript/exercise/code-completion/variables/ https://foxipa.com/en/javascript/exercise/code-completion/variables/ Complete each JavaScript snippet by supplying the missing declaration, assignment, or template substitution. Check every challenge as you go. https://foxipa.com/en/javascript/exercise/code-completion/numbers/ https://foxipa.com/en/javascript/exercise/code-completion/numbers/ Complete each JavaScript snippet by supplying the missing numeric expression or type-aware operation. https://foxipa.com/en/javascript/exercise/code-completion/expressions-and-operators/ https://foxipa.com/en/javascript/exercise/code-completion/expressions-and-operators/ Practice operators, short-circuiting, nullish coalescing, conditional expressions, and grouping by completing real JavaScript code. https://foxipa.com/en/javascript/exercise/code-completion/values-types-coercion-equality/ https://foxipa.com/en/javascript/exercise/code-completion/values-types-coercion-equality/ Practice explicit conversion, strict equality, NaN checks, nullish fallback, BigInt, SameValue, and numeric comparison by completing real JavaScript code. https://foxipa.com/en/javascript/exercise/code-completion/control-flow-and-declarations/ https://foxipa.com/en/javascript/exercise/code-completion/control-flow-and-declarations/ Practice branching, switch control, loop control, returns, exceptions, cleanup, and safe return syntax by completing real JavaScript code. https://foxipa.com/en/javascript/exercise/code-completion/scope-environments-closures/ https://foxipa.com/en/javascript/exercise/code-completion/scope-environments-closures/ Practice lexical scope, shadowing, closures, callbacks, loop bindings, and name resolution by completing real JavaScript code. https://foxipa.com/en/javascript/exercise/code-completion/function-objects-and-this/ https://foxipa.com/en/javascript/exercise/code-completion/function-objects-and-this/ Practice function objects, call-site this, arrow functions, call/apply/bind, and constructor calls by completing real JavaScript. https://foxipa.com/en/javascript/exercise/code-completion/objects-and-prototypes/ https://foxipa.com/en/javascript/exercise/code-completion/objects-and-prototypes/ Practice prototype creation, property ownership, lookup, shared methods, and descriptors. https://foxipa.com/en/javascript/exercise/code-completion/arrays/ https://foxipa.com/en/javascript/exercise/code-completion/arrays/ Practice transformations, selection, reduction, searching, non-mutating edits, materialization, and grouping with JavaScript arrays. https://foxipa.com/en/javascript/exercise/code-completion/property-descriptors-accessors-integrity/ https://foxipa.com/en/javascript/exercise/code-completion/property-descriptors-accessors-integrity/ Practice descriptor inspection, accessor definition, and object integrity operations. https://foxipa.com/en/javascript/exercise/code-completion/map-set-weak-collections/ https://foxipa.com/en/javascript/exercise/code-completion/map-set-weak-collections/ Practice Map association, Set membership and algebra, and WeakMap object-keyed metadata. https://foxipa.com/en/javascript/exercise/code-completion/proxy-reflect-metaprogramming/ https://foxipa.com/en/javascript/exercise/code-completion/proxy-reflect-metaprogramming/ Practice creating proxies and forwarding intercepted operations with Reflect. https://foxipa.com/en/javascript/exercise/code-completion/iterators-and-generators/ https://foxipa.com/en/javascript/exercise/code-completion/iterators-and-generators/ Practice the iterable protocol, generator control flow, delegation, and lazy iterator helpers. https://foxipa.com/en/javascript/exercise/code-completion/errors-defensive-control-flow/ https://foxipa.com/en/javascript/exercise/code-completion/errors-defensive-control-flow/ Practice throwing, preserving causes, cleanup, classification, aggregation, and propagation. https://foxipa.com/en/javascript/exercise/code-completion/promises/ https://foxipa.com/en/javascript/exercise/code-completion/promises/ Practice chaining and choosing Promise APIs by outcome contract. https://foxipa.com/en/javascript/exercise/code-completion/async-functions-and-iteration/ https://foxipa.com/en/javascript/exercise/code-completion/async-functions-and-iteration/ Practice async functions, await, error handling, async iteration, and Array.fromAsync. https://foxipa.com/en/javascript/exercise/code-completion/javascript-program-architecture/ https://foxipa.com/en/javascript/exercise/code-completion/javascript-program-architecture/ Practice focused APIs, dependency injection, composition roots, adapters, state ownership, and lifecycle boundaries. https://foxipa.com/en/javascript/exercise/code-completion/unicode-aware-strings/ https://foxipa.com/en/javascript/exercise/code-completion/unicode-aware-strings/ Practice code-point iteration, well-formedness, normalization, and Unicode-aware String APIs. https://foxipa.com/en/javascript/exercise/code-completion/global-object-standard-global-functions/ https://foxipa.com/en/javascript/exercise/code-completion/global-object-standard-global-functions/ Practice the remaining standard global access and function APIs. https://foxipa.com/en/javascript/exercise/code-completion/regular-expressions/ https://foxipa.com/en/javascript/exercise/code-completion/regular-expressions/ Practice patterns, captures, flags, match indices, Unicode properties, and global replacement. https://foxipa.com/en/javascript/exercise/code-completion/json-and-structured-data/ https://foxipa.com/en/javascript/exercise/code-completion/json-and-structured-data/ Practice JSON parsing, serialization, formatting, and transformation hooks. https://foxipa.com/en/javascript/exercise/code-completion/symbols-and-property-protocols/ https://foxipa.com/en/javascript/exercise/code-completion/symbols-and-property-protocols/ Practice Symbol keys, registry operations, reflection, and protocol hooks. https://foxipa.com/en/javascript/exercise/code-completion/dates-and-modern-time-temporal/ https://foxipa.com/en/javascript/exercise/code-completion/dates-and-modern-time-temporal/ Practice the core Date and Temporal APIs. https://foxipa.com/en/javascript/exercise/code-completion/internationalization-intl/ https://foxipa.com/en/javascript/exercise/code-completion/internationalization-intl/ Practice core ECMA-402 Intl services. https://foxipa.com/en/javascript/exercise/code-completion/arraybuffer-typedarrays-dataview/ https://foxipa.com/en/javascript/exercise/code-completion/arraybuffer-typedarrays-dataview/ Practice ArrayBuffer, TypedArrays, and DataView operations. https://foxipa.com/en/javascript/exercise/code-completion/sharedarraybuffer-atomics/ Sun, 27 Sep 2026 16:00:00 +0000 https://foxipa.com/en/javascript/exercise/code-completion/sharedarraybuffer-atomics/ Practice SharedArrayBuffer and Atomics operations. https://foxipa.com/en/javascript/exercise/code-completion/source-text-lexical-grammar-parsing/ https://foxipa.com/en/javascript/exercise/code-completion/source-text-lexical-grammar-parsing/ Practice recognizing source-level grammar constructs, directives, literals, comments, and statement boundaries. https://foxipa.com/en/javascript/exercise/code-completion/classes/ https://foxipa.com/en/javascript/exercise/code-completion/classes/ Practice class declarations, constructors, inheritance, public and private elements, and static initialization. https://foxipa.com/en/javascript/exercise/code-completion/execution-model-contexts-realms-jobs-agents/ https://foxipa.com/en/javascript/exercise/code-completion/execution-model-contexts-realms-jobs-agents/ Practice execution-model concepts with small JavaScript completions. https://foxipa.com/en/javascript/exercise/code-completion/explicit-resource-management/ https://foxipa.com/en/javascript/exercise/code-completion/explicit-resource-management/ Practice using declarations, disposal protocols, and disposable stacks. https://foxipa.com/en/javascript/exercise/code-completion/modern-ecmascript-update-pass/ https://foxipa.com/en/javascript/exercise/code-completion/modern-ecmascript-update-pass/ Practice selecting modern standardized ECMAScript APIs. https://foxipa.com/en/javascript/exercise/code-completion/weak-references-finalization-registry/ https://foxipa.com/en/javascript/exercise/code-completion/weak-references-finalization-registry/ Practice WeakRef, FinalizationRegistry, unregister tokens, and safe weak-lifetime handling.