flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.
flatMap() method first maps each element using a mapping function, then flattens the result into a new array. It is identical to a map followed by a flat of depth 1, but
flatMap is often quite useful, as merging both into one method is slightly more efficient.
Object.fromEntries() method transforms a list of key-value pairs into an object.
Note: Object.fromEntries only accept iterable (i.e) Object.fromEntries(iterable)
It will accept only Map or Array
4.String.trimStart() & String.trimEnd()
trimStart() method removes whitespace from the beginning of a string.
trimEnd() method removes whitespace from the end of a string.
You can think why another new method already there are two method
trimLeft() but it will be alias of above new methods
5.Optional Catch Binding
Allow developers to use try/catch without creating an unused binding.
You are free to go ahead make use of catch block without a param
Earlier it is mandatory to use param in catch block
toString() method returns a string representing the source code of the function.Earlier white spaces,new lines and comments will be removed when you do now they are retained with original source code
description property is a string returning the optional description of
8.Well Formed JSON.Stringify()
JSON.stringify from returning ill-formed Unicode strings.
Users with same rating retain their sorting order
Array#sort implementation is Chakra, which uses QuickSort for arrays with more than 512 elements (and stable insertion sort for anything else).
For more info read this article
10.JSON ⊂ ECMAScript (JSON Superset)
Extend ECMA-262 syntax into a superset of JSON.
JSON syntax is defined by ECMA-404 and permanently fixed by RFC 7159, but the DoubleStringCharacter and SingleStringCharacter productions of ECMA-262 can be extended to allow unescaped U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR characters.
For more info read this proposal
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