javascript - 从第一个索引中按顺序删除数组 javascript 值

Question

我有这个数组:

let items = ["apple", "orange", "watermelon", "blueberry", "lemon", "guava"];

我想从第一个索引中按顺序删除数组值。所以它会产生:

[ "apple", "orange", "watermelon", "blueberry", "lemon", "guava" ]
[ "orange", "watermelon", "blueberry", "lemon", "guava" ]
[ "watermelon", "blueberry", "lemon", "guava" ]
[ "blueberry", "lemon", "guava" ]
[ "lemon", "guava" ]
[ "guava" ]

我已经尝试过这段代码:

let items = ["apple", "orange", "watermelon", "blueberry", "lemon",   "guava"];

runLoop = async () => {
for(const item of items){
        await new Promise( resolve => setTimeout( resolve, 1000 ));
        console.log(items);
        remove(items, item);
        console.log('------------');
    }
 }

 function remove(array, element) {
  console.log('deleting '+element);
  const index = array.indexOf(element);
  array.splice(index, 1);
 }

但结果不是我所期望的，这是结果:

Array(6) [ "apple", "orange", "watermelon", "blueberry", "lemon", "guava" ]
Array(5) [ "orange", "watermelon", "blueberry", "lemon", "guava" ]
Array(4) [ "orange", "blueberry", "lemon", "guava" ] 

Answer 1

问题是可迭代数组是事件的 - 如果您使用 for..of 调用迭代器并在迭代器仍在使用时改变数组 ，迭代的结果项可能不直观 - 可能会遗漏一些指标。这有点像这里发生的事情:

let items = ["apple", "orange", "watermelon", "blueberry", "lemon",   "guava"];
for (let i = 0; i < items.length; i++) {
  console.log('item: ', items[i]);
  items.splice(i, 1);
}

循环只运行 3 次，因为您在遍历数组时从数组中删除了项目，所以一些指标会被跳过。

一种可能性是在用 for..of 调用迭代器时首先复制数组，这样迭代器将始终迭代原始数组中的每个项目数组顺序:

let items = ["apple", "orange", "watermelon", "blueberry", "lemon",   "guava"];

runLoop = async () => {
  for(const item of items.slice()){
    await new Promise( resolve => setTimeout( resolve, 300 ));
    console.log(items);
    remove(items, item);
    console.log('------------');
  }
}

function remove(array, element) {
  console.log('deleting '+element);
  const index = array.indexOf(element);
  array.splice(index, 1);
}
runLoop();