JS Essay

①Use {} curly braces to define an object, and define it in the form of key (attribute name):value (attribute value) inside curly braces.
Objects are composed of attributes, attributes are in the form of key-value pairs, and attributes are separated by commas.

②The concat() method can also be used to splice arrays
var array=['three','country']; 
var array2=['play','meaning']; 
console.log(array.concat(array2));// The result is: ['three', 'country', 'play', 'yi']
or string
var string='king'; 
string.concat('conceit')//result: king, conceit

③ Split the string character
String split
split() method, the usage is more diverse. Note that no matter which split method is used, the result is an array

typeof new Date() // "object"
typeof [] // "object"