js 计算交集

es6数组方法做交集

let a = new Set([1,2,3,[3,4,5]].flat());
let b = new Set([2,3,[5]].flat());
let c = [...a].filter(item => b.has(item));

结果：[2,3,5]

js for循环

function arr( a, b ) {
	let res = []
    for(let i = 0; i < a.length; i++){
    	for(let j = 0; j < b.length; j++){
        	if(a[i] === b[j]){
           		res.push(a[i])
            }
        }
    }
    return res//千万不要忘了return出去
}
arr([1,2,3],[3,4])//[2]