JS 数组查重

let arr1 = ['a', 'b', 'c', 'd'];
let arr2 = ['x', 'b', 'c', 'y'];
let long = arr1.length < arr2.length ? arr2 : arr1;
let short = arr1.length < arr2.length ? arr1 : arr2;
let str = "," + long.toString() + ",";
let result = [];
for(let i in short){
    if(str.indexOf("," + short[i] + ",") >= 0){
        result.push(short[i]);
    }
}
alert(result.toString()); // b, c


// 取出两个数组的不同元素
getArrDifference(arr1, arr2) {
    return arr1.concat(arr2).filter(function(v, i, arr) {
        return arr.indexOf(v) === arr.lastIndexOf(v);
    });
}

// 取出两个数组的相同元素
getArrEqual(arr1, arr2) {
    let newArr = [];
    for (let i = 0; i < arr2.length; i++) {
        for (let j = 0; j < arr1.length; j++) {
            if(arr1[j] === arr2[i]){
                newArr.push(arr1[j]);
            }
        }
    }
    return newArr;
}