TypedArray.prototype.findLastIndex()
TypedArray
实例的 findLastIndex()
方法以相反的顺序迭代类型化数组,并返回满足所提供的测试函数的第一个元素的索引。如果没有元素满足测试函数,则返回-1。该方法与 Array.prototype.findLastIndex()
的算法相同。
¥The findLastIndex()
method of TypedArray
instances iterates the typed array in reverse order and returns the index of the first element that satisfies the provided testing function. If no elements satisfy the testing function, -1 is returned. This method has the same algorithm as Array.prototype.findLastIndex()
.
Try it
语法
参数
返回值
描述
¥Description
详细信息请参见 Array.prototype.findLastIndex()
。此方法不是通用的,只能在类型化数组实例上调用。
¥See Array.prototype.findLastIndex()
for more details. This method is not generic and can only be called on typed array instances.
示例
查找类型化数组中最后一个素数的索引
¥Find the index of the last prime number in a typed array
以下示例返回类型化数组中最后一个素数元素的索引,如果没有素数,则返回 -1
。
¥The following example returns the index of the last element in the typed array that is a prime number, or -1
if there is no prime number.
function isPrime(element) {
if (element % 2 === 0 || element < 2) {
return false;
}
for (let factor = 3; factor <= Math.sqrt(element); factor += 2) {
if (element % factor === 0) {
return false;
}
}
return true;
}
let uint8 = new Uint8Array([4, 6, 8, 12]);
console.log(uint8.findLastIndex(isPrime));
// -1 (no primes in array)
uint8 = new Uint8Array([4, 5, 7, 8, 9, 11, 12]);
console.log(uint8.findLastIndex(isPrime));
// 5
规范
Specification |
---|
ECMAScript Language Specification # sec-%typedarray%.prototype.findlastindex |
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