js join split

array.join([separator])

let fruits = ['apple', 'banana', 'cherry'];
let sentence = fruits.join(' and '); // "apple and banana and cherry"
console.log(sentence);

string.split([separator[, limit]])

let sentence = "apple and banana and cherry";
let fruits = sentence.split(' and '); // ["apple", "banana", "cherry"]
console.log(fruits);

let sentence = "one,two;three|four";
let separators = /[,;|]/; // 正则表达式分隔符
let words = sentence.split(separators); // ["one", "two", "three", "four"]
console.log(words);

let arr = ['apple', null, 'banana', undefined, 'cherry'];
let cleanArr = arr.map(item => item || ''); // ["apple", "", "banana", "", "cherry"]
let sentence = cleanArr.join(' and '); // "apple and  and banana and  and cherry"
console.log(sentence);