用逗号和“and”连接数组

const input = ['one', 'two', 'three', 'four'];
const last = input.pop();
const result = input.join(', ') + ' and ' + last;
console.log(result);

function makeString(arr) {
  if (arr.length === 1) return arr[0];
  const firsts = arr.slice(0, arr.length - 1);
  const last = arr[arr.length - 1];
  return firsts.join(', ') + ' and ' + last;
}

console.log(makeString(['one', 'two', 'three', 'four']));
console.log(makeString(['one']));

const input1 = ['one', 'two', 'three', 'four'];
const input2 = ['A Tale of Two Cities', 'Harry Potter and the smth', 'One Fish, Two Fish, Red Fish, Blue Fish'];
const input3 = ['one', 'two'];
const input4 = ['one'];
const input5 = [];

const result = a => a.length > 1 
  ? `${a.slice(0, -1).join(', ')} and ${a.slice(-1)}` 
  : {0: '', 1: a[0]}[a.length];

console.log(result(input1));
console.log(result(input2));
console.log(result(input3));
console.log(result(input4));
console.log(result(input5));

let arrayToCustomStr = (arr, enableMutate) =>
{
    // Clone the received array (if required).
    let a = enableMutate ? arr : arr.slice(0);

    // Convert the array to custom string.
    let removed = a.splice(-2, 2);
    a.push(removed.join(" and "));
    return a.join(", ");
}

// First example, mutate of original array is disabled.
let input1 = ['one', 'two', 'three', 'four'];
console.log("Result for input1:" , arrayToCustomStr(input1));
console.log("Original input1:", input1);

// Second example, mutate of original array is enabled.
let input2 = ['one', 'two'];
console.log("Result for input2:", arrayToCustomStr(input2, true));
console.log("Original input2:", input2);

// Third example, lenght of array is 1.
let input3 = ['one'];
console.log("Result for input3:", arrayToCustomStr(input3));

// Fourth example, empty array.
let input4 = [];
console.log("Result for input4:", arrayToCustomStr(input4));

// Plus example.
let bob = [
    "Don't worry about a thing",
    "Cause every little thing",
    "Gonna be all right",
    "Saying, don't worry about a thing..."
];
console.log("Result for bob:", arrayToCustomStr(bob));

.as-console-wrapper {
    top: 0px;
    max-height: 100% !important;
}

const makeCommaSeparatedString = (arr, useOxfordComma) => {
  const listStart = arr.slice(0, -1).join(', ')
  const listEnd = arr.slice(-1)
  const conjunction = arr.length <= 1 
    ? '' 
    : useOxfordComma && arr.length > 2 
      ? ', and ' 
      : ' and '

  return [listStart, listEnd].join(conjunction)
}

console.log(makeCommaSeparatedString(['one', 'two', 'three', 'four']))
// one, two, three and four

console.log(makeCommaSeparatedString(['one', 'two', 'three', 'four'], true))
// one, two, three, and four

console.log(makeCommaSeparatedString(['one', 'two'], true))
// one and two

console.log(makeCommaSeparatedString(['one']))
// one

console.log(makeCommaSeparatedString([]))
//

const lf = new Intl.ListFormat('en');

console.log(lf.format(['Frank']));
// → 'Frank'

console.log(lf.format(['Frank', 'Christine']));
// → 'Frank and Christine'

console.log(lf.format(['Frank', 'Christine', 'Flora']));
// → 'Frank, Christine, and Flora'

console.log(lf.format(['Frank', 'Christine', 'Flora', 'Harrison']));
// → 'Frank, Christine, Flora, and Harrison'

// You can use it with other locales
const frlf = new Intl.ListFormat('fr');

console.log(frlf.format(['Frank', 'Christine', 'Flora', 'Harrison']));
// → 'Frank, Christine, Flora et Harrison'

const list = ['A', 'B', 'C', 'D'];

// With Oxford comma 
const lfOxfordComma = new Intl.ListFormat('en', {
  style: 'long',
  type: 'conjunction'
});
console.log(lfOxfordComma.format(list)); // → A, B, C, and D


// Without Oxford comma 
const lfComma = new Intl.ListFormat('en-GB', {
  style: 'long',
  type: 'conjunction'
});
console.log(lfComma.format(list)); // → A, B, C and D

let resultA4 = (list => list.length < 3 ? list.join(" and ") : [list.pop(), list.join(", ")].reverse().join(", and ")).call(this, ['one', 'two', 'three', 'four']);

let resultA2 = (list => list.length < 3 ? list.join(" and ") : [list.pop(), list.join(", ")].reverse().join(", and ")).call(this, ['one', 'two']);

let resultA1 = (list => list.length < 3 ? list.join(" and ") : [list.pop(), list.join(", ")].reverse().join(", and ")).call(this, ['one']);

let items = ['one', 'two', 'three', 'four'];

//If you can't mutate the list you can do this
let resultB = (list => list.length < 3 ? list.join(" and ") : [list.pop(), list.join(", ")].reverse().join(", and ")).call(this, items.slice());

// or this option that doesn't use call
let resultC = items.length < 3 ? items.join(" and ") : [items.slice(0, -1).join(", "), items.slice(-1)].join(", and ");

console.log(resultA4);
console.log(resultA2);
console.log(resultA1);
console.log(resultB);
console.log(resultC);