find

Grammar

find(callbackFn)
find(callbackFn, thisArg)

Params

• callbackFn:ArrayCallbackFn<boolean>

  为数组中的每个元素执行的函数。它应该返回一个真值来表示已经找到了匹配的元素。

• thisArg

  执行 callbackFn 时用作 this 的值。

Return

数组中第一个满足所提供测试函数的元素的值，否则返回 undefined。

Example

const inventory = [
  { name: "apples", quantity: 2 },
  { name: "bananas", quantity: 0 },
  { name: "cherries", quantity: 5 },
];

function isCherries(fruit) {
  return fruit.name === "cherries";
}

console.log(inventory.find(isCherries));
// { name: 'cherries', quantity: 5 }

findLast

find的反向查找

const inventory = [
  { name: "apples", quantity: 2 },
  { name: "bananas", quantity: 0 },
  { name: "fish", quantity: 1 },
  { name: "cherries", quantity: 5 },
];

// 库存低时返回 true
function isNotEnough(item) {
  return item.quantity < 2;
}

console.log(inventory.findLast(isNotEnough));
// { name: "fish", quantity: 1 }