雷雷

從下面的陣列 old 裡

var old = [
    {
        id: 1,
        name: 'css',
        type: 'html'
    },
    {
        id: 2,
        name: 'css',
        type: 'html'
    },
     {
        id: 3,
        name: 'javacript',
        type: 'code'
    },
    {
        id: 4,
        name: 'javacript',
        type: 'code'
    }
]

得到 new

var new = [
    {
        id: [1,2],
        name: 'css',
        type: 'html'
    },
     {
        id: [3,4],
        name: 'javacript',
        type: 'code'
    }
]

實作

var isEqual = (a, b) => a.name === b.name && b.type === b.type; 
var create = e => {
    e.id = [e.id]; 
    return e; 
}

var getNew = old => old.reduce((acc, cur) => {
    let hasItem = acc.some(e => {
        let temp = isEqual(e, cur); 
        if (temp) e.id.push(cur.id); 
        
        return temp; 
    });
    
    if (!hasItem) acc.push(create(cur))
    
    return acc; 
}, []);