js数组去重

Posted 2020-12-17 清梦徐徐丶莫

// 数组去重方法

let arr1 = Array.from(new Array(10000), (item, index) => {
	return index;
})

let arr2 = Array.from(new Array(5000), (item, index) => {
	return index + index
})

console.log([...arr1, ...arr2])

// 方法一：Array.filter() + indexOf
function distinct(a, b) {
	let arr = a.concat(b);
	return arr.filter((item, index) => {
		return arr.indexOf(item) === index
	})
}

// 方法二： for...of + includes()
function distinct(a, b) {
	let arr = a.concat(b);
	let result = [];
	for (let i of arr) {
		!result.includes(i) && result.push(i)
	}
	return result;
}

// 方法三：双重for循环
function distinct(a, b) {
	let arr = a.concat(b);
	for (let i = 0, len = arr.length; i < len; i++) {
		for (let j = i + 1; j < len; j++) {
			if (arr[i] === arr[j]) {
				arr.splice(j, 1);
				len--;
				j--;
			}
		}
	}
}

// 方法四：Array.sort()
function distinct(a, b) {
	let arr = a.concat(b);
	arr.sort(function(a, b) {
		return a - b;
	})
	let result = [arr[0]]
	for (let i = 1, len = arr.length; i < len; i++) {
		arr[i] !== arr[i - 1] && result.push(arr[i])
	}
	return result
}

// 方法五：for...of + Object
function distinct(a, b) {
	let arr = a.concat(b)
	let result = []
	let obj = {}

	for (let i of arr) {
		if (!obj[i]) {
			result.push(i)
			obj[i] = 1
		}
	}

	return result
}

// 方法六：es6的new set()
function distinct(a, b) {
    return Array.from(new Set([...a, ...b]))
}


console.log(distinct(arr1, arr2))

转载自 JS实现数组去重方法整理