Array.prototype.some()

¥Syntax

some(callbackFn)
some(callbackFn, thisArg)

¥Parameters

callbackFn

对数组中的每个元素执行的函数。它应该返回 truthy 值以指示元素通过测试，否则返回 falsy 值。使用以下参数调用该函数：

element

数组中当前正在处理的元素。

index

数组中当前正在处理的元素的索引。

array

调用了数组 some()。

thisArg Optional

执行 callbackFn 时用作 this 的值。参见 迭代法。

¥Return value

false，除非 callbackFn 返回数组元素的 truthy 值，在这种情况下，立即返回 true。

¥false unless callbackFn returns a truthy value for an array element, in which case true is immediately returned.

¥Description

some() 方法是 迭代法 方法。它为数组中的每个元素调用一次提供的 callbackFn 函数，直到 callbackFn 返回 truthy 值。如果找到这样的元素，some() 立即返回 true 并停止遍历数组。否则，如果 callbackFn 对所有元素返回 falsy 值，则 some() 返回 false。请阅读 迭代法 部分，了解有关这些方法一般如何工作的更多信息。

¥The some() method is an iterative method. It calls a provided callbackFn function once for each element in an array, until the callbackFn returns a truthy value. If such an element is found, some() immediately returns true and stops iterating through the array. Otherwise, if callbackFn returns a falsy value for all elements, some() returns false. Read the iterative methods section for more information about how these methods work in general.

some() 的作用类似于数学中的 "那里存在" 量词。特别是，对于空数组，无论任何条件它都会返回 false。

¥some() acts like the "there exists" quantifier in mathematics. In particular, for an empty array, it returns false for any condition.

callbackFn 仅针对已赋值的数组索引调用。稀疏数组 中的空槽不会调用它。

¥callbackFn is invoked only for array indexes which have assigned values. It is not invoked for empty slots in sparse arrays.

some() 不会改变调用它的数组，但 callbackFn 提供的函数可以。但请注意，数组的长度是在第一次调用 callbackFn 之前保存的。所以：

¥some() does not mutate the array on which it is called, but the function provided as callbackFn can. Note, however, that the length of the array is saved before the first invocation of callbackFn. Therefore:

• 当对 some() 的调用开始时，callbackFn 将不会访问任何超出数组初始长度添加的元素。
• 对已访问索引的更改不会导致再次对它们调用 callbackFn。
• 如果数组中现有的、尚未访问的元素被 callbackFn 更改，则传递给 callbackFn 的值将是该元素被访问时的值。已删除 个元素未被访问。

警告：上述类型的并发修改经常会导致代码难以理解，通常应该避免（特殊情况除外）。

¥Warning: Concurrent modifications of the kind described above frequently lead to hard-to-understand code and are generally to be avoided (except in special cases).

some() 方法是 generic。它只期望 this 值具有 length 属性和整数键控属性。

¥The some() method is generic. It only expects the this value to have a length property and integer-keyed properties.

¥Examples

¥Testing value of array elements

下面的示例测试数组中是否有任何元素大于 10。

¥The following example tests whether any element in the array is bigger than 10.

function isBiggerThan10(element, index, array) {
  return element > 10;
}

[2, 5, 8, 1, 4].some(isBiggerThan10); // false
[12, 5, 8, 1, 4].some(isBiggerThan10); // true

¥Testing array elements using arrow functions

箭头函数 为相同的测试提供了更短的语法。

¥Arrow functions provide a shorter syntax for the same test.

[2, 5, 8, 1, 4].some((x) => x > 10); // false
[12, 5, 8, 1, 4].some((x) => x > 10); // true

¥Checking whether a value exists in an array

为了模仿 includes() 方法的功能，如果该元素存在于数组中，此自定义函数将返回 true：

¥To mimic the function of the includes() method, this custom function returns true if the element exists in the array:

const fruits = ["apple", "banana", "mango", "guava"];

function checkAvailability(arr, val) {
  return arr.some((arrVal) => val === arrVal);
}

checkAvailability(fruits, "kela"); // false
checkAvailability(fruits, "banana"); // true

¥Converting any value to Boolean

const TRUTHY_VALUES = [true, "true", 1];

function getBoolean(value) {
  if (typeof value === "string") {
    value = value.toLowerCase().trim();
  }

  return TRUTHY_VALUES.some((t) => t === value);
}

getBoolean(false); // false
getBoolean("false"); // false
getBoolean(1); // true
getBoolean("true"); // true

¥Using the third argument of callbackFn

如果你想访问数组中的另一个元素，特别是当你没有引用该数组的现有变量时，array 参数非常有用。以下示例首先使用 filter() 提取正值，然后使用 some() 检查数组是否严格递增。

¥The array argument is useful if you want to access another element in the array, especially when you don't have an existing variable that refers to the array. The following example first uses filter() to extract the positive values and then uses some() to check whether the array is strictly increasing.

const numbers = [3, -1, 1, 4, 1, 5];
const isIncreasing = !numbers
  .filter((num) => num > 0)
  .some((num, idx, arr) => {
    // Without the arr argument, there's no way to easily access the
    // intermediate array without saving it to a variable.
    if (idx === 0) return false;
    return num <= arr[idx - 1];
  });
console.log(isIncreasing); // false

¥Using some() on sparse arrays

some() 不会在空槽上运行其谓词。

¥some() will not run its predicate on empty slots.

console.log([1, , 3].some((x) => x === undefined)); // false
console.log([1, , 1].some((x) => x !== 1)); // false
console.log([1, undefined, 1].some((x) => x !== 1)); // true

¥Calling some() on non-array objects

some() 方法读取 this 的 length 属性，然后访问其键为小于 length 的非负整数的每个属性，直到它们全部被访问或 callbackFn 返回 true。

¥The some() method reads the length property of this and then accesses each property whose key is a nonnegative integer less than length until they all have been accessed or callbackFn returns true.

const arrayLike = {
  length: 3,
  0: "a",
  1: "b",
  2: "c",
  3: 3, // ignored by some() since length is 3
};
console.log(Array.prototype.some.call(arrayLike, (x) => typeof x === "number"));
// false

¥See also

• core-js 中 Array.prototype.some 的 Polyfill
• 索引集合 指南
• Array
• Array.prototype.every()
• Array.prototype.forEach()
• Array.prototype.find()
• Array.prototype.includes()
• TypedArray.prototype.some()