如何在 JS 函数中使用 setTimeout 减慢列表的输出

Question

该程序将输出数组中包含的 5 个元素中的 4 个元素的组合。但它会立即执行，我希望它执行得更慢，每行后等待 1 秒。我已经尝试过很多方法来添加 setTimeout(function()content,1000*i) 它对我不起作用，相关问题也无济于事。任何人都可以帮忙解决吗？

const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];
const three = [];
three.length = 4;

function combine(a, b, c) {
  if (b === 0) {
    console.log(`${three.join(" ")}`);
    return;
  }
  for (let i = c; i <= a.length - b; i++) {
    three[three.length - b] = a[i];
    combine(a, b - 1, i + 1);
  }
}

combine(vegetables, three.length, 0);

Answer 1

我相信你正在寻找的是显示数组列表的延迟效果。您需要做的就是将 setTimeOut 放入循环中，它会完美运行。

const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];
const three = [];
three.length = 4;

function combine(a, b, c) {
  if (b === 0) {
    console.log(`${three.join(" ")}`);
    return;
  }
  for (let i = c; i <= a.length - b; i++) {

    setTimeout(()=>{  //------------------------> Place settimeout here
    three[three.length - b] = a[i];
    combine(a, b - 1, i + 1);
    },1000*i)

  }
}

combine(vegetables, three.length, 0);

Answer 2

您可以尝试这样的操作：

const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];
const three = [];
const combined = [];
three.length = 4;

function sleep(ms) {
  return new Promise(function (resolve) {
    setTimeout(resolve, ms);
  });
}

function combine(a, b, c) {
  if (b === 0) {
    combined.push(`${three.join(" ")}`);
    return;
  }

  for (let i = c; i <= a.length - b; i++) {
    three[three.length - b] = a[i];
    combine(a, b - 1, i + 1);
  }
}

(async function main() {
  console.log('started');
  combine(vegetables, three.length, 0);

  for (const entry of combined) {
    console.log(entry);
    await sleep(1000);
  }
})();

Answer 3

您可以使用for await ... of

const veg = ["carrot", "tomatoes", "potatos", "celery", "pepper"];
const combo = [false, true, true, true, true]; // 4 out of 5

const t0 = performance.now();
function display(){
  const t1 = performance.now();
  console.log(filter(veg, combo), ` time = ${t1-t0}`);
}

async function* nextPerm(a){
  do {
    await new Promise(res => setTimeout(res, 1000));
    yield a;
  } while(nextPermutation(a));
}

let g = nextPerm(combo);
(async function() {
  for await (let next_combo of g) {
    display();
  }
})();

function filter(a, select) {
  return a.filter((_e,i) => select[i]);
}

function nextPermutation(array, first = 0, last = array.length-1) {
  if(first>=last){
    return false;
  }
  let i = last;
  for(;;){
    const i1 = i;
    if(array[--i]<array[i1]){
      let i2 = last+1;
      while(array[i]>=array[--i2]);
      [array[i], array[i2]] = [array[i2], array[i]];
      reverse(array, i1, last);
      return true;
    }
    if(i===first){
      reverse(array, first, last);
      return false;
    }
  }
}

function reverse(array, i=0, j=array.length-1) {
  while (i < j)
    [array[i++], array[j--]] = [array[j], array[i]];
}

如何在 JS 函数中使用 setTimeout 减慢列表的输出

how to slow down the output of a list using setTimeout inside of JS function

javascript

arrays

function

delay

output