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Search, Filter & Sort

The three operations behind every table you will ever build, and the traps in each.

Intermediate15 min on the clock6 graded checks · 100 pointsJavaScript + TypeScript

Graded by running your code against real cases.

What you build

searchUsers(list, term) across name and email
The search is case-insensitive and safe with an empty term
filterUsers(list, status) — "All" means no filtering
sortUsers(list, sortBy, direction) both ways
None of them may reorder the list they were given

Done means

Search, filter and sort all behave, and the caller's array comes back untouched.

How it is graded

Published in full, before you start — every point is one of these and there is nothing else. Each one runs your code; it is not a search for keywords.

Search matches name and email+20Array methods
Search ignores case+15Array methods
An empty search returns everything+10Array methods
filterUsers narrows by status, and "All" does not+15Array methods
sortUsers orders both ways+25Array methods
Sorting does not reorder the caller's array+15Not mutating your inputs

What it teaches

Array methodsbeginner

map, filter, find and reduce replace almost every loop you would otherwise write — knowing which one returns what is the single highest-leverage thing in JavaScript.

Not mutating your inputsintermediate

sort() and reverse() change the array you gave them, which is how a filter quietly reorders the caller's data — copy first, and the bug never exists.

The rest of JavaScript + TypeScript

Product CatalogBeginner · 10 min Shopping CartBeginner · 15 min The Mutation TrapBeginner · 10 min From SQL to JavaScriptIntermediate · 20 min API Data TransformationIntermediate · 12 min PaginationBeginner · 12 min Async States & DebounceAdvanced · 20 min