Object extension

1.1 Concise representation of attributes

1.2 Attribute name expression

1.3 the Object is ()

It’s used to determine if it’s strictly equal

1.4 Extension operators for objects

It’s just a copy of an object

1.5 the Object. The assign ()

1.6 in

1.7 Object Traversal

1.7.1 the for the in

1.7.2 Object. The keys ()

1.7.3 Object. GetOwnPropertyNames ()

1.7.4 Reflect. Ownkeys ()

2. Array extension

2.1 Class array/pseudo-array

2.1.1 Class arrays cannot use array methods

2.1.2 How to Check whether it is an array

2.1.3 Converting a class array to an array

2.2 Array. The from ()

This method converts a pseudo-array of class arrays into a real array

2.3 Array) of ()

2.3.1 the new Array

2.3.2 Array) of ()

2.4 copyWithin

2.5 the fill

2.6 includes

The disadvantage of indexof is that it does not detect NaN in an array