关于两数组,求出两数组中相同的的对象

 这个要算6次才能算出来

let a = [{
        id: ‘1‘,
        name: ‘1‘
    }, {
        id: ‘2‘,
        name: ‘2‘
    }, {
        id: ‘3‘,
        name: ‘3‘
    }]
    let b = [{
            id: ‘3‘,
            name: ‘3‘
        },
        {
            id: ‘1‘,
            name: ‘1‘
        }
    ]
    let c = new Map()
    a.map(item => {
        c.set(item.id, item)
    })
    let d = []
    let e = []
    let num = 0
    b.map(item => {
        num++
        if (c.has(item.id)) {
            d.push(item)
            console.log(num)
        } else {
            e.push(item)
        }
    })

 这个才计算两次