js array 查找元素

let arr = [1, 2, 3, 4, 5];
let index = arr.indexOf(3);
console.log(index); // 输出: 2

let arr = [1, 2, 3, 4, 5];
let exists = arr.includes(3);
console.log(exists); // 输出: true

let arr = [1, 2, 3, 4, 5];
let found = arr.find(element => element > 3);
console.log(found); // 输出: 4

let arr = [1, 2, 3, 4, 5];
let foundIndex = arr.findIndex(element => element > 3);
console.log(foundIndex); // 输出: 3

let arr = [1, 2, 3, 4, 5];
arr.sort((a, b) => a - b); // 排序
let binarySearch = (arr, target) => {
    let left = 0;
    let right = arr.length - 1;
    while (left <= right) {
        let mid = Math.floor((left + right) / 2);
        if (arr[mid] === target) return mid;
        if (arr[mid] < target) left = mid + 1;
        else right = mid - 1;
    }
    return -1;
};
let index = binarySearch(arr, 3);
console.log(index); // 输出: 2