This is not a feature of JavaScript but is Chrome's way of displaying uninitialized indexes in arrays (and array-like objects). For example, if you console.log the following −Exampleconsole.log(Array(100))Output[undefined × 100]This is better than printing [undefined, undefined, undefined,...] as it is more readable.

JavaScript allows you to add very advanced features to your web applications. For example, Drawing and manipulating graphicsAudio and Video APIs like HTMLMediaElement, the Web Audio API, and WebRTC allow you to do really interesting things with multimedia such as creating custom UI controls for playing audio and video, displaying ... Read More

According to MDN, An arrow function expression is a syntactically compact alternative to a regular function expression, although without its own bindings to the this, arguments, super, or new.target keywords. Arrow function expressions are ill suited as methods, and they cannot be used as constructors.There are 3 subtle differences in ... Read More

Javascript arrays are 0-indexed. This means that the first element is at the 0th position. The last element is at the length-of-array - 1th position. So we can access these elements using −Examplearr[0] // First element arr[arr.length - 1] // last element For example, let arr = [1, 'test', {}, ... Read More

Javascript specification doesn't specify a particular algorithm to be used in the Array.sort implementation. This is left on the implementor to decide. So different JS engines use different sorting algorithms.Mozilla(Spider Monkey JS engine) uses mergeSort. You can see the code written for it in C in the Mozilla repository: https://dxr.mozilla.org/seamonkey/source/js/src/jsarray.cWebKit(Chrome, ... Read More

The unshift method adds the element at the zeroeth index and shifts the values at consecutive indexes up, then returns the length of the array.The push() method adds the element at end to an array and returns that element. This method changes the length of the array.Examplelet fruits = ['apple', ... Read More

The shift method removes the element at the zeroeth index and shifts the values at consecutive indexes down, then returns the removed value. If the length property is 0, undefined is returned.The pop() method removes the last element from an array and returns that element. This method changes the length ... Read More

The basic difference between slice and splice is −splice() changes the original array on which it is called and returns the removed item(s) in an array as a new array object.slice() doesn't change the original array and also returns the array sliced.Example// splice changes the array let arr = [1, ... Read More

Shallow copy and deep copy are language agnostic. Shallow copies duplicate as little as possible. A shallow copy of a collection is a copy of the collection structure, not the elements. With a shallow copy, two collections now share the individual elements.Examplelet innerObj = {    a: 'b',    c: ... Read More

The radix sort algorithm distributes integers into buckets based on a number's significant digit or value (the radix). The radix is based on the number system of the values of the arrays. Let us look at how it can be implemented −Examplefunction radixSort(arr) {    // Find the max number ... Read More