You've effectively required more than twice the memory than necessary to get the value to simply assign to the array (none of that was done in place). JS vs jQuery jQuery Selectors jQuery HTML jQuery CSS jQuery DOM You're effectively returning a modified array that was sliced three times and concatenated together with two objects between the three sliced arrays. JS JSON JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON Server JSON PHP JSON HTML JSON JSONP JS AJAX AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples JS Web APIs Web API Intro Web Forms API Web History API Web Storage API Web Worker API Web Fetch API Web Geolocation API JS Browser BOM JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies JS HTML DOM DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM Forms DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists For example, an array of length 7 can have 3 elements in it. The number of elements in an array cannot exceed the length of an array, though the number of elements can be less than the length of the array. JS Async JS Callbacks JS Asynchronous JS Promises JS Async/Await The length property of an array defines the maximum number of elements that could be present in an array. JS Classes Class Intro Class Inheritance Class Static JS Functions Function Definitions Function Parameters Function Invocation Function Call Function Apply Function Closures
JS Objects Object Definitions Object Properties Object Methods Object Display Object Accessors Object Constructors Object Prototypes Object Iterables Object Sets Object Maps Object Reference JS Versions JS Versions JS 2009 (ES5) JS 2015 (ES6) JS 2016 JS 2017 JS 2018 JS IE / Edge JS History The reduce () method does not reduce the original array. JS Tutorial JS HOME JS Introduction JS Where To JS Output JS Statements JS Syntax JS Comments JS Variables JS Let JS Const JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Events JS Strings JS String Methods JS String Search JS String Templates JS Numbers JS Number Methods JS Arrays JS Array Methods JS Array Sort JS Array Iteration JS Array Const JS Dates JS Date Formats JS Date Get Methods JS Date Set Methods JS Math JS Random JS Booleans JS Comparisons JS Conditions JS Switch JS Loop For JS Loop For In JS Loop For Of JS Loop While JS Break JS Iterables JS Sets JS Maps JS Typeof JS Type Conversion JS Bitwise JS RegExp JS Errors JS Scope JS Hoisting JS Strict Mode JS this Keyword JS Arrow Function JS Classes JS JSON JS Debugging JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words Any element whose index is greater than or equal to the new length will be removed.