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Front End Engineer · Web Developer · Full Stack Engineer
CounterWarm Up Question
Build a simple counter which increments whenever a button is clickedStackFree
Implement a stack data structure containing the common stack methodsType UtilitiesFree
Implement utilities to determine primitive variable types in JavaScriptInsertion SortFree
Implement a function that performs an insertion sortBinary SearchFree
Implement a function that performs binary search on an array of numbersDebounceFree
Implement a function to limit how many times a function can be executed by delaying the execution of the function until after a specified time after its last execution attemptHeap SortFree
Implement a function that performs an heap sortQueueFree
Implement a queue data structure containing the common queue methodsFlattenFree
Implement a function that recursively flattens an array into a single level deepMerge SortFree
Implement a function that performs a recursive merge sortPromise.allFree
Implement the Promise.all() function that resolves to an array of results if all the input elements are resolved or rejects otherwiseQuick SortFree
Implement a function that performs a recursive quick sortTodo ListFree
Build a Todo list that lets users add new tasks and delete existing tasksTopological SortFree
Implement a function that performs a topological sortDeep CloneFree
Implement a function that performs a deep copy of a valueArray.prototype.squarePremium
Implement a custom Array.prototype.square() method which squares the values in an arrayGetPremium
Implement a function to safely access deeply-nested properties in JavaScript objectsOncePremium
Implement a function that accepts a callback and restricts its invocation to at most onceSelection SortPremium
Implement a function that performs a selection sortUnique ArrayPremium
Implement a function to remove all duplicate values from an arrayAccordionPremium
Build an accordion component that a displays a list of vertically stacked sections that each contain a title and content snippetArray.prototype.filterPremium
Implement the Array.prototype.filter() methodArray.prototype.mapPremium
Implement the Array.prototype.map() methodArray.prototype.reducePremium
Implement the Array.prototype.reduce() methodFunction.prototype.bindPremium
Implement the Function.prototype.bind() function that creates a new function with the this keyword set to a provided valueGenerate TablePremium
Generate a table of numbers given the rows and columnsjQuery.cssPremium
Implement a jQuery-like function that sets the style of a DOM elementProgress BarPremium
Build a progress bar component which shows the percentage completion of an operationProgress BarsPremium
Build a list of progress bars which fill up gradually when they are added to the pagePromise.racePremium
Implement the Promise.race() function that resolves or rejects when any of the input elements are resolved or rejectedSumPremium
Implement a function that sums numbers by accepting a number and allows for repeated calling with more numbers until it is not called with any numberTemperature ConverterPremium
Build a temperature converter widget that converts temperature values between Celsius and FahrenheitCurryPremium
Implement a function which transforms a function which takes multiple arguments into a function that can be repeatedly called with only one argument at a timeLimitPremium
Implement a function that accepts a callback and restricts its invocation to at most N timesTabsPremium
Build a tabs component that a displays a list of tab elements and one associated panel of content at a timeThrottlePremium
Implement a function to control the execution of a function by limiting how many times it can execute over timeAccordion IIPremium
Build an accessible accordion component that has the right ARIA roles, states, and propertiesAccordion IIIPremium
Build a fully accessible accordion component that has keyboard support according to ARIA specificationsAnalog ClockPremium
Build an analog clock where the hands update and move like a real clockCamel Case KeysPremium
Implement a function to convert all the keys in an object to camel caseClassnamesPremium
Implement a function which conditionally joins CSS class names togetherCurry IIPremium
Implement a function which transforms a function which takes multiple arguments into a function that can be repeatedly called with any number of argumentsDebounce IIPremium
Implement a debounce function that comes with a cancel method to cancel delayed invocations and a flush method to immediately invoke themEvent EmitterPremium
Implement a class that can subscribe to and emit events which triggers attached callback functionsEvent Emitter IIPremium
Implement a class that can subscribe to and emit events which triggers attached callback functions. Susbcription objects are returned and can unsubscribe itselfgetElementsByTagNamePremium
Implement a function to get all DOM elements which match a tagGrid LightsPremium
Build a grid of lights where the lights deactivate in the reverse order they were activatedHTML SerializerPremium
Implement a function to serialize an object into a HTML string with indentationIdentical DOM TreesPremium
Implement a function to determine if two DOM trees are the samejQuery Class ManipulationPremium
Implement a set of jQuery-like functions that manipulates classes on a DOM elementLike ButtonPremium
Build a Like button that changes appearance based on the statesList FormatPremium
Implement a function that formats a list of items into a single readable stringProgress Bars IIPremium
Build a list of progress bars which fill up gradually in sequence, one at a timePromise.allSettledPremium
Implement the Promise.allSettled() function that resolves to an array of outcomes when all the input elements are either resolved or rejectedPromise.anyPremium
Implement the Promise.any() function that resolves when any of the input elements are resolvedSquash ObjectPremium
Implement a function that returns a new object after squashing the input object into a single level of depthStar RatingPremium
Build a star rating component that shows a row of star icons for users to select the number of filled stars corresponding to the ratingTabs IIPremium
Build a semi-accessible tabs component that has the right ARIA roles, states, and propertiesTabs IIIPremium
Build a fully accessible tabs component that has keyboard support according to ARIA specificationsText SearchPremium
Implement a function to highlight text if a searched term appears within itTraffic LightPremium
Build a traffic light where the lights switch from green to yellow to red after predetermined intervals and loop indefinitelyDeep EqualPremium
Implement a function that determines if two values are equalDigital ClockPremium
Build a 7-segment digital clock which shows the current timegetElementsByClassNamePremium
Implement a function to get all DOM elements that contain the specified classesProgress Bars IIIPremium
Build a list of progress bars which fill up gradually concurrently, up to a limit of 3Text Search IIPremium
Implement a function to highlight text if searched terms appear within itSignup FormPremium
Build a signup form that does validation on user details and submits to a back end APIStopwatchPremium
Build a stopwatch widget which can measure how much time has passedCurry IIIPremium
Implement a function which transforms a function which takes variadic arguments into a function that can be repeatedly called with any number of argumentsProgress Bars IVPremium
Build a list of progress bars which fill up gradually concurrently, up to a limit of 3 and allows for pausing and resumingData SelectionPremium
Implement a function to filter rows of data matching a specified requirementTable of ContentsPremium
Implement a function to construct a table of contents from a HTML documentDeep Clone IIPremium
Implement a function that performs a deep copy of a value, but also handles circular referencesJSON.stringifyPremium
Implement a function that converts a JavaScript value into a JSON string